I use simple controls, edited to make it more like Armored Core 3... I just used to own at AC3, so I'm not too good with the controls in this game. I just picked up ACFA after playing up to Last Raven. Does that make me a terrible player? No, I just have to get the hang of the new controls and new things they added. I enjoy the game, it's proven to be challenging. I used to do East Coast tournaments for Armored Core MoA and AC2AA(When they stopped hosting tournaments). I may goof off with the B control scheme, but I'm liking the way I have it right now.
I also don't use autolock, just because I hate how it conflicts with my instincts to turn the other way if someone is circling me, and not follow the way their rotating. If that makes me a bad player, so be it. I hardly care what e-peen sucking people have to say(and that's what that makes you, if you want to flame me for options I may or may not use).
In my opinion, it's all about play style and not so much over trivial things like options and button configurations.
I haven't played much online yet(just got the game today), but I still think that if you can optimize the AC you built and really know how to cover weaknesses, you should be able to win 1vs1. The game doesn't seem to be unbalanced. I've seen HW move relatively fast compared to older games.
The only problem I have with the game is that you can be overweight now. It seems to slightly overpower lighter models, because the extra weight doesn't seem to bother their movement speed. I think this added more challenge to the older games.