Well most guys will shoot better with a slimmer grip, less chance to torque the bow. Most target bows don't even have grips or sideplates on them from the factory, for that specific reason.

But if you're seriously thinking about it.....Loesch(sp?) builds custom grips at bowgrips.com. And there a few guys on archerytalk.com that build them too. There are some fine pieces of work on both sites if you look.