I don't use retention holsters because I have literally hundreds of thousands of draws in competition using tension holsters, and I'm used to the feel. I've never had any trouble dropping trou -- you do have to pay attention -- but I've been carrying a gun since the dawn of time.
In truth, leather is more comfortable than kydex...Lou Alessi's holsters are as near to perfect IWBs as I've ever used, but Lou has enough orders to last him two forevers. At SHOT, I got an AWB from a new holstermaker and student of Lou's, John Ralston. It is a beautiful holster for my PARA Carry 9, and I'm going to wring it out. You guys will hear my results here first!
Given my druthers, I'll take the easy way out and use a Comp-Tac paddle, which conceals well under a jacket or a vest. Back when I had "leisure time," I would periodically go out and shoot an IDPA match with my IWB.
On practicing retention techniques, I'm for it with a caveat...training time is always limited, and I would rather see you guys put the time into the basics first. You'll probably see some retention stuff in THE BEST DEFENSE Season 2...or maybe 3. In the meantime, focus on a homily from trainer Dane Burns: "Distance is good; more distance is better."
Michael B