I own the 40c and bought it for summer carry in shorts and tee shirts...
No issues or problems with it or the M&P45 I have also.
For IWB holster that is very comfortable, look at the CrossBreed SuperTuck. They make them in left hand versions.
Also Brommeland Max-Con V IWB holsters are super high quality and are very comfortable. They cost a little more, but why get cheap when it comes to a holster? It makes no sense and in the long run, 2 or 3 cheap holsters that don't feel all that good nor fit right, will cost you the same as a good one...