Hmmm...okay, my 226 has the standard grip on it [had on it, actually...now it wears the Hogue wraparound grip, which is even larger] so I can't state definitely that the E2 grips wouldn't do the trick for the OP. However, I would still maintain that the M&P, esp. with the small backstrap [that comes packaged with every gun] would probably be a better choice. The M&P is designed to fit a wide variety of hands, after all. Also, let's keep in mind that trigger reach is a big factor in handgun fit. The extra distance from backstrap to trigger on the trigger-cocking Sig could mean a big difference to someone with small hands. Please understand that none of these comments are to put down the Sig. I am _very_ impressed with mine...it's obviously a top-quality handgun. I'm just not convinced it's for everybody.
Of course, the really final answer is that the OP should try handling a bunch of different guns and see what feels best to him.