I shoot USPSA, IDPA, Steel Challenge, and Man-on-Man Steel matches with my Kimbers. Major power factor ammo for USPSA and IDPA, and minor power factor ammo for the steel matches. Shooting a 42 oz gun with 135 PF ammo is almost like cheating.
In IDPA, you would be shooting in CDP class. Make sure you practice drawing from concealment before you go to your first match. I have seen more than one new IDPA shooter come out and fumble their first draw by getting tangled up in their clothing, and being DQ'ed for it. Take your time, and be safe your first match. IDPA is a lot of fun, but give the other sports a try also. I think the more disciplines you shoot, the better overall shooter you become. Each sport will teach you something different. For me, IDPA emphasizes more "tactical" type shooting, and is all about accuracy. USPSA is all about accuracy, but also adds speed into the equation. The steel matches emphasize 1 shot hits, and fast reloads
Personally, I like USPSA over IDPA, simply because I get to shoot more rounds at a USPSA match. The local IDPA match never goes over 100 rounds, but my USPSA club typically shoots 150+ rounds.