I shoot a lot of IDPA matches and while I've seen almost every rig that is legal there are a few suggestions. One is that I would not recommend an IWB holster. In big matches there is a lot of holster and unholstering, especially on a cold range and the IWB holsters slow things down a lot, especially when your nerves are up. I would also agree that it starts to become a safety issue.
Two, it can be a paddle holster, use the IDPA link above to see what's legal. The general rule is that with a concealment garment on, hands held out level to the sides the firearm is not visable. There also must not be any space between the holster and the body. That means that while wearing the rig if you look down the firearm should tuck in tight to your body without any daylight showing. The trigger and trigger guard must also be fully covered, so there is no risk of accidently catching the trigger and setting it off, again, take a look at the rules link above to see, but these are the basics.
I own a blackhawk that has the locking lever, I would not recommend for competition, but I wear it in conceal carry. I also have a Fobus paddle holster that is better for competion, and is also very comfortable. My first IDPA holster was a Uncle Mikes Kydex holster. They're cheap, tough and durable, if you're just trying things out I couldn't recommend them more as they are probably the most affordable quality holster out there... Just my two cents, thanks zac.
