Heads-up against an unknown player that just seems incredibly tight to me and I strongly disagree.

Even against an arguably overly strong value/semibluff range (which assumes no unexpected bluffs or weird spew, neither of which can be ruled out), Gorak and I have shown we have ~38%-43% equity. Folding to 2:1 in this heads-up spot just seems like throwing money away, even if we may underrealize our equity on the river as villain can probably successfully bluff a lot of cards. (I feel like this may be an argument for shoving this turn, tbh. Villain only needs to have a handful of folds/spew for it to be profitable. On this turn, I feel like I'd rather potentially make a relatively small pot equity mistake and gain information on villain's play than fold the best hand on the river.)

This spot really depends on the math of how we do against their entire range, and saying we only have 10 outs to win is just not going to be accurate often enough to be the sole heuristic here. If we're going to be playing so tight to say that we only have 10 outs to win this pot, I feel like we might as well say we only have four outs: As and any non-spade 5.

But that's just too tight!

Realistically, villain can have a lot of different holdings here that we have a wide range of equity against.

There are only a few hands that dominate us in every way, and when we're not up against those, we often have either the right price or a really significant equity edge! This is why we have to look at our equity versus their range, and—when Gorak and I have done so—folding seems extremely unappealing given the odds overall.

Furthermore, we're really only in horrible shape against a range of As*s:(QQ, Q8, 88, 44, 22, AQ), and that doesn't weigh heavily enough in villain's range to make me assume that it's what we need to worry about. Also, combinatorically (using PPT's Count with relevant ranges), we dominate villain far more often than they dominate us. So even if they're value raising the turn, they're value-eviscerating themselves pretty often.

So, without a read and knowing that a random player at PLO25 can value-eviscerate themselves easily (especially HU), I just can't fold this turn and I think it would be a really big mistake to fold.

And having thought about it more, I think I just GII on the turn. There's enough value in seeing their hand or seeing them fold that I don't think we're making a big mistake by shoving turn (and we're going to be GII as a favorite often enough that it's sometimes a good value play, of course).

Even against As*s:(QQ, Q8, 88, 44, 22, AQ) (again, worst case scenario), we have about 21% equity. In that specific scenario, if I'm not mistaken we're paying like 20bb for really valuable information. That's not great in isolation, but if we're going to be playing with this opponent (especially HU) for any significant amount of time, that investment can pay off really well compared to being in the dark about what they check-raised this turn with (which we won't learn if we fold and may not learn if we call). (And again again, this is worst case scenario.)

Cheers! It's been an interesting hand to chew on, so I appreciate you posting it.