I bought my M&P Shield 9 for the purpose of CC, I practiced with it before taking the course, passed my test with it, scored a 250 out of 250 with it! Since I recieved my plastic it has been my EDC and now I IDPA with it!
If you have a CHL, I think getting involved in IDPA is a great way to learn, and to develop skill with the pistol that is intended to save your life. I have been shooting at targets since 1989 when I was a 20 yr old kid. My first day at a IDPA match last month I felt like a noob that never handled a gun before... I quickly realized my limitations, and now I'm hard set to learn & develop proper markmanship, safe gun handling while moving, reloading, properly using cover all while under the "stress" of your friends watching & being timed...
I honestly feel the Shield 9 in the right hands is a very competitive pistol and is just as accurate as the rest of them. The only downfall for me so far is trying to find a dual mag holster for shield magazines, cant find any and what kills my score in part is me fumbling around in my front cargo shorts pocket for the other mag. You're gonna need at least 3-8 round mags for IDPA. The holster I use is a kydex OWB by Fobus, which works very well...
In addition, Freedom munitions 124 gr. FMJ's work very, very well in the Shield for IDPA.