SXS shooters put more into stock fit as, at least from my experience shooting one requires instinctive response. A lot of single barrel shooters aim at the target, some get very good at it. This style of shooting compensates for stock fit. I can't imagine they would be tops in competitive clays, though.
Even with a massive 10 gauge SXS, I tend to shoot better when a quick response was necessary. I read something about getting on target with rifles, a heavy British double rifle properly fitted was on target first, a relatively light "handy" lever action rifle (one stock fits all) was on target last.
