Black is outboarded so much that I'd be inclined to play 8/7/2 in both positions.

I know I'm probably getting one (or both!) of them wrong. I see there's various duplication arguments one can make for varying the play, but I'm not really seeing a clear argument.

By the way, the upcoming cube is going to magnify any equity differences between the best two plays.

I assume this is a DMP situation, or that white thought that he/she was too good (why is the cube still centered?). Either slotting the five, or hitting loose on the ace and slotting the bar, yield 23 shots to your opponent. There are several differences however: 1) hitting on the ace leaves two blots. However, hit-and-make combos are greatly reduced so, if you do get hit, you are likely to get return shots. You might even get lucky enough to make the bar if you are hit on the ace, giving you some needed structure! 2) Slotting allows more combos to both hit and make the four. However, the five is a more valuable point to make.
Generally speaking, leaving two blots is worse than leaving one blot. Here, however, you are almost as likely to get gammoned with one checker closed out, as with two checkers closed out. And, it is totally unclear to me that gammon matters at all-if it is DMP. Since fewer hit and make combos are possible with ace point hit, and the bar point is arguably as valuable here as the five point-perhaps even more so, I would consider that play. However, it does leave a permanent liability for us on the ace. We must play ugly, follow Stick's advice, and make the ace asap. In both situations, I guess, I would slot the bar and hit on the ace, but i do see the duplication with twos here. I really don't have a clue, but, this is my thought process here