I found the c-tac somewhat uncomfortable at times... But considering that I carry a 5" 1911, it performed quite well. My biggest gripe was the area that shields the thumb safety would dig into my side at times. I'd imagine this could be fixed with the moleskin suggestion. If you have love handles at all, this will be a must. A quality gun belt is especially important with the c-tac, since the "outrigger" straps get pretty flexible once they're broken in. Combined with the C shaped belt clips, I could see it being quite unstable if it's on a lighter belt (which is probably obvious).
I carried the c-tac daily (for about 6 mo) while waiting for my Milt Sparks VM2. After carrying both, I prefer the VM2 for most situations. Even though it may be a bit thicker, it seems smaller simply because of the construction. The ctac seems more like a "rig" with all the clips, leather, plastic, etc. The VM2 is one smooth piece. With a thicker double stack I might favor the c-tac due to it's slimmer profile... but not with the 1911. Then it's a matter of Kydex vs. leather. The rigid kydex on the c-tac seems to grab the pistol in a few "hot spots" whereas the leather hugs the entire pistol like a glove. The ctac has adjustable tension from "fall out loose" to "get a crowbar tight". The VM2 was secure to my liking as-is... thankfully... since there's no adjustment.
I still use the ctac on the range for it's holstering/draw speed, and the VM2 for daily carry.
HTH.