Yup. Big-time. Anybody passing this off as just good old-fashioned cheating has it way wrong. This is a different territory all together. It's the optics more than anything else; it's not realistically THAT much of an advantage, if at all, most of the time. It's more along the lines, IMO, of corking the bat, where the perceived/actual benefits are far more dwarfed by he risk/work involved. Without doing any research on the matter at all, I don't think that comparison is even remotely close to accurate. I think the sign stealing presents a substantial advantage and I'm pretty sure corked bats actually hurt rather than help (which you sort of alluded to), at least in terms of power/hitting distance.