Thank you for your reply _Z_. I read through your reply here and in the linked thread.
My confusion is maybe based on a few assumptions, which you might be able to point out where I've gone wrong?
1. XG's "Cube Information" is the same thing as market window i.e. take/drop/too-good points, i.e. depicted here:
https://bkgm.com/articles/mpd.html#gammon_potential
2. Market window is based on a simple formula from match equity tables (shown in XG's Analyze -> Match Equity Table from the menu bar:
https://www.bkgm.com/faq/Matches.htm...my_take_point_
3. XG's cube error value probably takes into account "early/late cost ratio," more or less (although the way XG solves for these values is over my head.) For example, even though the 2a-2a market window linked above shows 30-70, it is known to be correct to double when you have 50.1% or greater winning chances typically.
Perhaps comparing "Cube Information" and "Cubeful Equities"/errors is comparing apples and oranges? So in other words, in another example shown below, even though I made the right move according to the market window (double), were I to roll out every possible ending to the game, it would have shown I somehow would end up with more wins with no-double decision.