Analyzed in Rollout  No redouble  Redouble/Take 
Player Winning Chances:  51.51% (G:5.65% B:0.24%)  51.66% (G:6.16% B:0.28%) 
Opponent Winning Chances:  48.49% (G:18.87% B:0.18%)  48.34% (G:22.02% B:0.13%) 
Cubeless Equities  0.036  +0.515 
Cubeful Equities 
No redouble:  +0.513 (0.002)  กำ0.003 (+0.510..+0.515) 
Redouble/Take:  +0.515  กำ0.003 (+0.512..+0.517) 
Redouble/Pass:  +1.000 (+0.485) 

Best Cube action: Redouble / Take 
Rollout details 
20736 Games rolled with Variance Reduction. Moves: 3ply, cube decisions: XG Roller


Double Decision confidence:  84.9% 
Take Decision confidence:  100.0% 
Duration: 11 hours 10 minutes 
eXtreme Gammon Version: 2.10, MET: Kazaross XG2
1.  XG Roller++  15/9 6/1*  eq: +0.529 
 Player: Opponent:  51.00% (G:6.82% B:0.19%) 49.00% (G:20.22% B:0.10%)  

2.  XG Roller++  10/4 9/4  eq: +0.374 (0.155) 
 Player: Opponent:  48.14% (G:4.66% B:0.12%) 51.86% (G:15.29% B:0.13%)  

3.  XG Roller++  20/9  eq: +0.309 (0.220) 
 Player: Opponent:  47.18% (G:4.00% B:0.11%) 52.82% (G:17.59% B:0.09%)  

4.  XG Roller++  20/15 20/14  eq: +0.230 (0.300) 
 Player: Opponent:  45.64% (G:2.50% B:0.03%) 54.36% (G:17.29% B:0.10%)  

5.  XG Roller++  9/3 8/3  eq: +0.168 (0.362) 
 Player: Opponent:  42.34% (G:4.19% B:0.11%) 57.66% (G:18.98% B:0.14%)  

6.  XG Roller++  15/9 10/5  eq: +0.156 (0.373) 
 Player: Opponent:  41.77% (G:3.95% B:0.11%) 58.23% (G:15.73% B:0.13%)  

Kudos to Othellosan for another superb quiz.
In this post, I discuss Problem 1 from the recent 2015 quiz.
In the first (lefthand) position above, the 20k rollout suggests it is likely  though by no means certain  that Blue "should" have redoubled before rolling. I trust nobody will lose sleep over this, but some may find it interesting.
In the second (righthand) position above, the XGR++ evaluation supports N (Near, 15/9 6/1*) as the best play, and it is a "wipeout" (the Ballard/Weaver error scale term for a play that is better than the second best play by at least .100). Othello's webposted rollout confirms the same order of plays, with the error sizes being .177, .244, .326, .371 and .396. (I would have posted it if I had the file.)
In the first (lefthand) prevariant below, I've altered White's buriedspare position by 1 pip. This time, it is almost certainly proper for Blue to roll without redoubling.
The second (righthand) variant below is a rollout of the 65 with that minor spare alteration. The margins are noticeably tighter (compare .128, .192, .266, .333 and .353 to the green numbers above), but the N play can still easily boast the status of "wipeout."
My nitpicky point is that with a slight spare alteration (2pt to 3pt), it is possible to eliminate the possible cube controversy, albeit with some sacrifice in bestplay clearance margin.
Analyzed in Rollout  No redouble  Redouble/Take 
Player Winning Chances:  50.53% (G:5.34% B:0.23%)  50.74% (G:5.67% B:0.25%) 
Opponent Winning Chances:  49.47% (G:19.44% B:0.22%)  49.26% (G:22.62% B:0.15%) 
Cubeless Equities  0.063  +0.460 
Cubeful Equities 
No redouble:  +0.473  กำ0.008 (+0.466..+0.481) 
Redouble/Take:  +0.460 (0.014)  กำ0.008 (+0.452..+0.468) 
Redouble/Pass:  +1.000 (+0.527) 

Best Cube action: No redouble / Take 
Percentage of wrong pass needed to make the double decision right: 2.5% 
Rollout details 
5184 Games rolled with Variance Reduction. Dice Seed: 31027603 Moves: 3ply, cube decisions: XG Roller


Double Decision confidence:  99.2% 
Take Decision confidence:  100.0% 
Duration: 3 hours 57 minutes 
1.  Rollout^{1}  15/9 6/1*  eq: +0.509 
 Player: Opponent:  49.63% (G:7.44% B:0.34%) 50.37% (G:24.43% B:0.21%)  Conf.: กำ 0.011 (+0.498...+0.520)  [100.0%] Duration: 31 minutes 50 seconds 

2.  Rollout^{1}  10/4 9/4  eq: +0.381 (0.128) 
 Player: Opponent:  47.62% (G:5.43% B:0.20%) 52.38% (G:18.71% B:0.25%)  Conf.: กำ 0.009 (+0.372...+0.390)  [0.0%] Duration: 28 minutes 48 seconds 

3.  Rollout^{1}  20/9  eq: +0.316 (0.192) 
 Player: Opponent:  46.71% (G:4.59% B:0.16%) 53.29% (G:19.38% B:0.10%)  Conf.: กำ 0.009 (+0.308...+0.325)  [0.0%] Duration: 30 minutes 30 seconds 

4.  Rollout^{1}  20/15 20/14  eq: +0.243 (0.266) 
 Player: Opponent:  45.54% (G:2.90% B:0.09%) 54.46% (G:18.53% B:0.16%)  Conf.: กำ 0.008 (+0.235...+0.251)  [0.0%] Duration: 38 minutes 48 seconds 

5.  Rollout^{1}  9/3 8/3  eq: +0.176 (0.333) 
 Player: Opponent:  41.88% (G:4.65% B:0.15%) 58.12% (G:21.22% B:0.21%)  Conf.: กำ 0.008 (+0.168...+0.184)  [0.0%] Duration: 31 minutes 54 seconds 

6.  Rollout^{1}  15/9 10/5  eq: +0.156 (0.353) 
 Player: Opponent:  41.04% (G:4.42% B:0.17%) 58.96% (G:18.50% B:0.20%)  Conf.: กำ 0.010 (+0.146...+0.165)  [0.0%] Duration: 34 minutes 20 seconds 


^{1} 1296 Games rolled with Variance Reduction. Moves: 3ply, cube decisions: XG Roller

Next, I respectfully submit Variant 2 below (with one of Blue's 6pt spares moved back to his 8pt). I find this problem even more difficult, because (a) Blue has the option of making an inside point without leaving a blot in his outer board, and (b) There is one fewer spare on the 6pt, making the acepoint hit less attractive.
I changed the score to gammon go for two reasons. One, there can be no criticism of cube action. Two, it increases the margin cleared by the best play from .055 (rollout at original match score situation, not shown) to the .070 you see below. [I noticed that of the ten 2015 problems, the smallest such margin is a blowout .068  Othello seems to hold these margins to a high standard.]
1.  Rollout^{1}  15/9 6/1*  eq: +0.290 
 Player: Opponent:  54.99% (G:9.53% B:0.53%) 45.01% (G:25.77% B:0.11%)  Conf.: กำ 0.007 (+0.283...+0.297)  [100.0%] Duration: 11 minutes 04 seconds 

2.  Rollout^{1}  9/3 8/3  eq: +0.220 (0.070) 
 Player: Opponent:  53.88% (G:7.13% B:0.39%) 46.12% (G:17.62% B:0.12%)  Conf.: กำ 0.005 (+0.215...+0.225)  [0.0%] Duration: 9 minutes 38 seconds 

3.  Rollout^{1}  20/9  eq: +0.192 (0.099) 
 Player: Opponent:  53.39% (G:6.19% B:0.27%) 46.61% (G:19.26% B:0.13%)  Conf.: กำ 0.006 (+0.186...+0.197)  [0.0%] Duration: 9 minutes 22 seconds 

4.  Rollout^{1}  10/4 9/4  eq: +0.177 (0.113) 
 Player: Opponent:  52.44% (G:6.41% B:0.31%) 47.56% (G:20.91% B:0.11%)  Conf.: กำ 0.005 (+0.172...+0.182)  [0.0%] Duration: 10 minutes 03 seconds 

5.  Rollout^{1}  20/15 20/14  eq: +0.128 (0.162) 
 Player: Opponent:  52.46% (G:3.95% B:0.15%) 47.54% (G:18.69% B:0.11%)  Conf.: กำ 0.005 (+0.123...+0.133)  [0.0%] Duration: 8 minutes 43 seconds 

6.  Rollout^{1}  15/9 10/5  eq: +0.063 (0.228) 
 Player: Opponent:  47.17% (G:5.96% B:0.34%) 52.83% (G:22.92% B:0.05%)  Conf.: กำ 0.005 (+0.057...+0.068)  [0.0%] Duration: 9 minutes 41 seconds 


^{1} 1296 Games rolled with Variance Reduction. Moves: 3ply, cube decisions: XG Roller

I do not claim my variants to be superior to the original position; I'm not sure how Othello balances the criteria. However, I am interested in his opinion. As it's his quiz, I naturally defer to his judgment.
Finally, below I offer a pair of variants that contrast each other. Variant 3 (lefthand) has the same match score, cube placement and board position as Othello's original problem, except Blue's 5pt is moved back to his 11pt. Variant 4 (righthand) has that point nudged back slightly further, to the 12pt.
If there is sufficient interest, I'll try to find time to post variants of other Othelloquiz positions.
Nack
1.  Rollout^{1}  15/9 6/1*  eq: +0.511 
 Player: Opponent:  49.98% (G:7.31% B:0.50%) 50.02% (G:29.14% B:0.45%)  Conf.: กำ 0.023 (+0.488...+0.534)  [100.0%] Duration: 42 minutes 33 seconds 

2.  Rollout^{1}  20/9  eq: +0.361 (0.150) 
 Player: Opponent:  47.26% (G:5.82% B:0.27%) 52.74% (G:27.67% B:0.14%)  Conf.: กำ 0.021 (+0.340...+0.382)  [0.0%] Duration: 35 minutes 00 second 

3.  Rollout^{1}  20/15 20/14  eq: +0.157 (0.355) 
 Player: Opponent:  43.51% (G:3.36% B:0.12%) 56.49% (G:29.71% B:0.30%)  Conf.: กำ 0.014 (+0.143...+0.170)  [0.0%] Duration: 48 minutes 20 seconds 

4.  Rollout^{1}  10/4 9/4  eq: +0.105 (0.406) 
 Player: Opponent:  40.16% (G:4.93% B:0.23%) 59.84% (G:28.81% B:0.37%)  Conf.: กำ 0.010 (+0.095...+0.115)  [0.0%] Duration: 45 minutes 30 seconds 

5.  Rollout^{1}  15/9 11/6  eq: +0.076 (0.435) 
 Player: Opponent:  39.26% (G:4.48% B:0.19%) 60.74% (G:24.76% B:0.39%)  Conf.: กำ 0.011 (+0.065...+0.087)  [0.0%] Duration: 44 minutes 45 seconds 

6.  Rollout^{1}  11/5 10/5  eq: +0.041 (0.470) 
 Player: Opponent:  39.28% (G:4.85% B:0.22%) 60.72% (G:35.93% B:0.74%)  Conf.: กำ 0.010 (+0.032...+0.051)  [0.0%] Duration: 43 minutes 43 seconds 

7.  Rollout^{1}  9/3 8/3  eq: 0.031 (0.542) 
 Player: Opponent:  36.15% (G:4.92% B:0.22%) 63.85% (G:31.04% B:0.39%)  Conf.: กำ 0.010 (0.041...0.021)  [0.0%] Duration: 43 minutes 16 seconds 


^{1} 1296 Games rolled with Variance Reduction. Moves: 3ply, cube decisions: XG Roller

1.  Rollout^{1}  20/9  eq: +0.236 
 Player: Opponent:  44.14% (G:5.60% B:0.34%) 55.86% (G:30.96% B:0.11%)  Conf.: กำ 0.014 (+0.223...+0.250)  [100.0%] Duration: 39 minutes 13 seconds 

2.  Rollout^{1}  15/9 6/1*  eq: +0.189 (0.047) 
 Player: Opponent:  42.04% (G:6.01% B:0.35%) 57.96% (G:32.02% B:0.28%)  Conf.: กำ 0.016 (+0.173...+0.206)  [0.0%] Duration: 53 minutes 32 seconds 

3.  Rollout^{1}  20/15 20/14  eq: +0.039 (0.197) 
 Player: Opponent:  40.42% (G:3.28% B:0.09%) 59.58% (G:31.97% B:0.15%)  Conf.: กำ 0.011 (+0.028...+0.050)  [0.0%] Duration: 52 minutes 17 seconds 

4.  Rollout^{1}  10/4 9/4  eq: 0.004 (0.240) 
 Player: Opponent:  37.50% (G:4.75% B:0.18%) 62.50% (G:31.13% B:0.56%)  Conf.: กำ 0.010 (0.014...+0.006)  [0.0%] Duration: 46 minutes 44 seconds 

5.  Rollout^{1}  15/9 12/7  eq: 0.057 (0.293) 
 Player: Opponent:  37.37% (G:5.01% B:0.21%) 62.63% (G:45.37% B:0.50%)  Conf.: กำ 0.012 (0.069...0.045)  [0.0%] Duration: 41 minutes 40 seconds 

6.  Rollout^{1}  9/3 8/3  eq: 0.073 (0.309) 
 Player: Opponent:  35.22% (G:4.89% B:0.12%) 64.78% (G:33.53% B:0.40%)  Conf.: กำ 0.011 (0.083...0.062)  [0.0%] Duration: 43 minutes 09 seconds 


^{1} 1296 Games rolled with Variance Reduction. Moves: 3ply, cube decisions: XG Roller
