The holster must allow the gun to be removed and reholstered. If your IWB will remain open so that you can re-holster the gun again it will be fine to use. I have shot IDPA at ARC and other ranges many times. I may not make it Sunday but good luck!!
Excellent. My Kholster has a Kydex body on it and will work fine. At IDPA, do they make you "drop the hammer" on an empty chamber with no magazine? I think I have heard this somewhere. If that is the case, I need to disengage my mag disconnect for the match.