The problem with "concealed carry gear", unless you are talking IWB which of course, isn't legal for USPSA at all, everyone has a different opinion of what a "concealed carry rig" is. While I might think one holster is fine for my carry, someone else may not.
The thing about USPSA, just about any safe holster will work, same with mag pouches, for IDPA this just isn't true.
I do agree with you on something RickB, jump in and do them both. I shoot USPSA primarily, my local club has IDPA every couple of months, yet I still learn something at every match, whether its USPSA or IDPA.
I will say, USPSA will help you with the speed aspect of IDPA. IDPA will help with the accuracy part of USPSA...they both go hand-in-hand.