I'm personally going to go with 9mm in Classic gun.
1) I just want to buy a 9mm 1911
2) it's cheaper to shoot, if don't care to be champ, but still competitive
3) it is competitive, in these regards.
3a) extra 2 rounds will help on some stages,
3b) even if stage design is 8rnd friendly, many times the extra 2 shots come in useful not to have to mag change if extra shot is require on steel, or if hit a no shoot, and need a follow up shot (without running dry),
3c)if partially covered target and want to put 3 rnds in 1-2 targets for security (without running dry),
4) possibly if can maintain same steady shooting speed and movement that you'd with a .40, but with a 9mm, maybe you'll have more A's instead of C's or more C's instead of D's, due to the much softer recoil of the 9mm, thus being easier to shoot, less recoil, less flinching, etc.... as others said, if going to shoot same # of A's and C's etc.. then should go major. But is my above statement true, that you maybe able to shoot more accurately at decent speed (of one own level of skill) ?
Cause there is a difference in how you shoot a 130 PF gun compared to a 175 Pf gun.
Now many here have stated they tried that and found better to go to .40 major, and maybe that's better, but worth trying both and having fun finding which works is best for you.
If I go to match and I think match set up is not good for minor, than I'll switch to shooting standard div. with my edge, if allowed too. Or just shoot it man ! There's no free trip to Greece as a prize.