If you wear an undershirt it's a non issue IMO. The texture of the P30 is nice for getting a good grip on the pistol, and comes in handy when you get a little sweaty on those hotter range days.I have heard the texture complaint of the P30 but am honestly not that concerned but maybe I should be.
I've handled the HK45c, but would like to do the same with a USPc .45 as I believe the grip is a little larger than the 9mm/.40 version. As for LEM, if I get the USPc, that will be the first thing done to it.442, I own many handguns and HK's. I carried the LEM P2000 in 40 cal for DHS for many years. I just got my 45C and I absolutely love it. I use a IWB holster and it is so comfortable. To me 9mm is just a waste of time. I think go big or go home. .45 all the way. Just my 2 cents. I have large hands and the HK comes with the different sized backstraps and it fits my hand like a glove with the M size installed. Get one you won't regret it! I also highly recommend the LEM light trigger, once you get used to it, as we all should be practicing with our carry guns, you will love it as I do!