I've been using a horsehide Theis IWB to carry a full-sized steel pistol for, umm, probably a year and a half now. I, too, have to cinch my belt down pretty snug, but I've never had a problem with the Kydex shell collapsing when the gun's unholstered. I think mine squeaked at first, too. Either the squeak went away, or I quit noticing it. Not sure which.
A gunfight is not the time to learn new skills.
If you ever have a real need for more than a couple of magazines, your problem is not a shortage of magazines. It's a shortage of people on your side of the argument. -- Art Eatman