I've got two SD's and three M&P's. I have installed Apex kits in the M&P's. All are 100% reliable... I surprise myself how much I like the SDs, for their thin profile and good handling. I don't disagree with the statements in this thread -- each person has valid perceptions -- but mine are a little different: I don't see the two series of pistols competing with each other, both are good at where they fit, and I have room in my safe for all of them...

Can't wait for the new S&W single-stack 9mm to come out at the SHOT Show.