Saying that not many stages after the first stage you shot at Sharon, didn't benefit if had 10 rnds, is not true....cause every array of targets, or stage, you may miss, or hit a penalty target, need extra shot on a steel, etc.. and having 2 more rounds as back up on any given situation (not having to static reload and throw off your game plan), is a benefit it itself and will come in handy for sure !!
35 yard stage...8 rounds...very likely you felt one or two pull left or right and would want to take a follow up shot or two..and you only have 9, instead of 11
stage after that, 8 rounds with no shoots inbetween, of which many people hit one of them (not going to admit I did

), and you may need two more shots...
the last stage on upper range had 10 targets....so you do the math on that one....
Another thing, if, and this is an if...(of which guys currently shooting 9mm in classic can reply to), if you can shoot more "A's" due to the less recoil, and easier to follow, etc... and maybe even get couple more A's or C's instead of a D, due to this...and maybe even slightly faster in some instances (due again to the lighter recoil), may result in better score than if you yourself with your abilities would have with a major power factor recoiling gun ??
It's not only if stage design is 8 rnd friendly, cause many times you'll need +1 or +2...or more... to finish an array... The difficult part is determining which for sure, would be best for you ? ?
I'm leaning towards giving the 9mm in classic a try...and If I don't think I'm shooting as well in results, then I'll switch to major.... I've shot major SS gun from 1995 to 2010... so I have something to gauge how I'll be doing with the 9mm... if your new to the game and not sure, then you'll have to buy both guns and figure it out
I'm not a believer that in all scenarios in the world, that if one this is the most common, that it has to be the right choice for you too... you have to test both and find what's right for you.