OK, got them in front of me. Comparing the two, the leather of the Supertuck is thinner, as it's 1 layer, it NEEDS the Combat Cut, and is less adjustable, tension can't be adjusted, and looks like a cheaper holster; but the clips are better, it can accept any length 1911, and the way the kydex is riveted on makes it not collapsing while wearing. It seems to have a larger opening for the pistol. The cowhide seems to scratch easier.
The MTAC was the holster that had the bending/collapsing problem, but is clearly the holster that is more expensive. Multiple layers of leather, the kydex is screwed through the leather, and the backs of the screws are shielded by a layer of leather from contact. their clips are more adjustable, and more options for different clips are available (I originally bought the C clips, but hated them as my belt was too narrow, and went back to the stock clips). However, the bottom of the clips poke me. I guess I could trim them to length once I decided how high I wanted to wear the holster. the kydex is formed to an exact 3" 1911. It's just that the only area that isn't a double layer of leather is in the vertical middle of the holster, so it flexes there closing off the opening for the gun. The MTAC also (middle adjustment holes) has the gun riding slightly higher. It also flexes out when the gun is in, as it seems more affected by the thumb safety. With my around the house use, it looks like new, while the Crossbreed has scratches in the leather from the thumb safety.
I like the MTAC engineering better, and for EDC where I'm not drawing my gun ever, I may wear it. However, for a class where I'll be drawing and re-holstering a lot, it's not useful for me. That said, a non IWB holster is generally more comfortable, and you can have your belt as tight as you'd like. I'm so impressed with the MTAC, I'm thinking that getting the all kydex CTAC and seeing if it fixes the main problem with the MTAC. The Supertuck is going back to Crossbreed for the Combat Cut.
Still, I wonder about comfort. the Crossbreed may lose comfort with the Combat Cut, and the CTAC may not be as comfortable as the MTAC.
In the end, I disqualified both the Crossbreed and the CompTac and ended up wearing a BladeTech Kydex holster, their Ultimate Concealment Holster, for the class. It stayed where I mounted it, didn't collapse, was easy to draw and holster, and is a more compact package (for good or bad) as it has only one belt loop and 1 adjustment (cant).
Next on my list, if I can find one, is a Versa Max 2, in lefty, for either a 3" 1911 or a Kahr P9. Will the extra bulk of an all leather holster bother me?
This is why MB and most gunnys have a box full of holsters, and something Michael mentioned before starting TV that he wanted to help others with (HINT, HINT 10 seasons later).