Carry a mag in a pocket??? Cell phone maybe, but never a mag. Want to know why?? 3 quick examples.
One: small piece of plastic tooth pick that the guy had put in his pocket so as not to litter somehow got into his mag through a witnes hole, jammed the mag after the reload; cost the guy several months in the hospital, but the one round that did chamber and fire eventually worked.
Two: loose .45 Colt mag in pocket got a penny slid in between top bullet and mag body, rapidly inserted and since the mag was full it bound up the gun and mag, slide wouldn't retract, couldn't strip the mag, wouldn't go bang. Result no penalty except getting to watch the instructor...me, beat the gun apart with a dead blow hammer so he could keep taking the course.
Three: loose +2 base plate on Glock mag snagged the pocket as the mag was withdrawn. Result, ripped pocket, flood of extra ammo, spring, follower, etc. hit ground, judicious amount of running and luck saved the guys life, but lost a really nice car.
Do what you want, but I always carry a mag in a holder. As for ruining your draw stroke, learning bad habits etc. if you practice both you will be good at both. I usual carry IWB I use a Blade Tech holster at belt level for competition, I haven't noticed any degredation in my draw stroke speed with either one while switching back and forth, and while we are visiting this whole Martial Artist/Gamer thing think about this, Life , as in a match, will be ONE draw after that the skill sets of shooting are the same so lets not make any big deal out of a single event, and concentrat on the evolving event. KurtM