RE: S&W M&P vs. Glock
Just to throw my .02 in,check out the para ordnance Lda series. They are available in aluminum alloy frame,real lifetime warranty that's not even needed,and have the smoothest,lightest dao trigger on this planet!
If you want something even smaller,the rohrbaugh 9mm is 12.8 oz,and size of a big seecamp (actually smaller than most .380s),and make excellent "Jesus" guns. By that I mean that if it comes down to point that I have to draw this gun-SOMEBODY'S gunna meet Jesus quickly! lol