The holster looks fine.
IDPA rule 8.6.C:
D. For male shooters only, ammunition carriers must hold the loading devices (magazines) such that a ¾ inch dowel placed between the shooter and the device contacts both the shooter and the device simultaneously.
I think that rules out the Quad-Mag Pouch.
You can use two double mag pouches. The rear mag pouch has to be behind the centerline, and must be empty when "Stand By" is called. In the rear mag pouch, I have one mag for the Barney round (which then goes into a pocket), and one for the gun. The front mag pouch is for reloads. Any extra mags have to be in your pocket.
As far as mag changes, you can dump an empty mag from slide-lock on the ground, but a tactical reload requires retention of the mag. You can just drop it into a pants pocket. Putting it back into the mag pouch is a
VERY BAD idea!
