The Barreta is a fine pistol. So is the M&P. In my experience, the Barreta is a dream to shoot. I find it to be very accurate. I have found the 92's and 96's (40 cal version) do require 1911 type mantenance.
The trigger pull on the Barreta in the single action mode is crisp. Have shot a few 96's which were DA only. These were former police guns and I understand why those dept's traded them. The pull is very, very long and probably pulled at 8-9 lbs.

I have found the M&P triggers to be on the mushy side, require less mantenance and are very reliable. The weight of the M&P is also a plus over the 92. The adjustable grips are a plus for the M&P also.

All things considered, I would probably lean toward the Smith mainly because of the grip fit. My 92 is now an occassional range gun and nothing more,but I would not trade it for anything.