I've given this recommendation many times and never had anyone disappointed with it. You cannot go wrong with Blade Tech. Specifically, Blade Tech's Classic OWB. Where it can get tricky is which belt attachment to choose. Since IDPA eschews the use of over/under competition belts, and the holster must go on the belt that holds up your pants, the Stingray Loop is the way to go. Either the adjustable one so you can have some flexibility with belt width, or the fixed width one if you consistently wear the same width belt.
Using this belt attachment allows you to "bridge" belt keepers on your pants for the optimum holster position. Since there is usually a belt loop aligned with the pants side seam - which pretty much is the body centerline as defined by IDPA rules - using the Stingray loop allows you to thread your belt through the rear holster slot, then the belt loop on the centerline, and then the forward holster slot. This gives you the correct holster position, plus holds the holster close to your body thanks to the belt loop behind the holster. The spread of the holster slots also distributes the weight of the rig over a broader area.
I assume that you'll be using this at SJSC and QSC. I'd shoot those matches if they didn't start so darn early. If you saw me, you'd realize I am in great need of as much beauty sleep as I can get. If you forward me your e-mail address via a PM, I'll send you a general schedule of weekend IDPA and USPSA matches in NJ and PA.
Adios,
Pizza Bob