~$1200 vs ~$650 it better be.
Wha?
Unless things have drastically changed, I routinely see Sig P226s in their standard configuration, sometimes with night sights, going for 1000 bucks and M&Ps going around 650 to 700. That's 30% to 35% of a price difference, not 50% like has been claimed.
I paid full retail for my MK25. I wanted the short extractor, the coolness of the MK25, the three Mec-Gar magazines, and the night sights.
It's likely that the M&P is the better
value the same way a 3-series is a better value than a 5-series, but I don't think it's a better gun. The Sigs have proven extremely accurate, easy to maintain, etc.
I'll give it to S&W though; they actually have a somewhat usable warranty in Canada whereas Sig likely does not.
I've never handled the M&P but apparently it's a great choice ergonomics wise, lots of converted Glock owners.