This has been hashed pretty throughly but I guess I'll throw in my 2 cents worth. I've never shot USPSA (would like to) but have shot 8-10 IDPA matches. I had been shooting either an XDM40 or XDM9. Both are ESP (enhanced service pistol). I don't get the logic but it has to do with what happens to the striker internally. The XD/XDMs are considered single action. Having shot Glocks and M&Ps, the trigger action to the operator is very similar. That said, Glocks and M&Ps are in SSP (stock service pistol) and are considered double action as are Sigs, Berettas, and all the DA/SA handguns. I recently bought an M&P Pro 9 for the sole purpose of shooting IDPA. I did if for a couple of reasons. First has to do with gaming the system to an extent. If stay in IDPA you need to eventually shoot a "classifier" round. This essentially establishes your "handicap" so they will know which classification to place you under in an official match. To make marksman (the lowest classification) you have to shoot the course of fire in 210 seconds or better in SSP. If you shoot ESP, you only have 190 seconds to make marksman. I don't know if I'll ever shoot a major match but would rather be shooting in SSP. I also like the "auto forward" feature of the M&P. When you aggressively seat a new magazine at slide lock, the slide releases forward very easily. This equates to time in a match. Other manufacturers may or may not do it but I find that an advantage. Finally, although my Pro is new, I think I shoot it more accurately than my XDMs (which I love like my children). I think the 5" barrel and associated longer sight radius is at least part of the reason.