Quick CC holster question.

So I just picked up a S&W M&P 40c, the problem I am having is that the only one available to me here has the thumb safety. To those of you who might have more experience with this, how much of a comfort loss should I expect? Also are there any specific type of IWB holsters I might look into in order to alleviate this problem, if any?

Pull the safety out...takes about 5 minutes. If you don't like the open notches in the frame speed shooter specialties sells the frame plugs for $3 each.

Thanks, I appreciate the help there.

The answer, as always, is "it depends."

For IWB holsters with a leather backing (Crossbreed Supertuck, Galco KingTuk, White Hat, Theis, CompTac, etc), the backing should prevent any discomfort.

For OWB holsters, discomfort should be minimal if any.

For IWB holsters without a backing, it depends on your body type. Bigger "muffin top" probably means more contact and more discomfort.

YMMV.

Personally, I find IWB/Paddle holsters of any type just too awkward and uncomfortable, period. I've even tried making several versions of my own, just to work around that issue,with little luck.
IWB OR OWB, though, I've rarely had any comfort issues that had anything to do with thumb-safeties. My .45 had ambi thumb-safeties, and I hardly notice them when worn, either way. Nor have I ever had any issues of the thumb levers moving when carried, regardless of my own movements.

I haven't noticed a difference using IWB holsters when one gun has had an external safety and the other has not. If you find IWB to be comfortable in general, then I doubt you will notice a difference as well.

I'v got a comptac & while my M&P9c doesnt have that safety it would have leather between it & me if it did and I doubt I'd feel a thing.