For IWB I have three different holsters and use only one due to comfort size and quality and it is the Comp Tac Minotaur MTAC with finished leather on both sides and also a smaller holster than the Crossbreed which I have but only use to hold my weapons that I am not using for carry and also what is called a Shielded Holster much like the Crossbreed but too wide and with unfinished leather on the back side is not really that comfortable and also does the same as the Crossbreed!
Hands down the Minotaur MTAC is the best most comfortable and with fast shipping, I even have one for my Shield40!