I've applied an all-black alpha to my skin for testing reasons and found that it had no effect on wearing, my skin still wears normally. I've exported as TGA from photoshop and imported using DTX5 (or w/e it's called).
And another thing, how do you keep wearing off of the pic related? In other m4a4 skins I've seen the texture seems to apply over that part. And in the software I use (substance painter) the image is also applied cleanly over this part, but when I view my skin in the workbench it becomes scratched up and the default m4 texture bleeds through. I've checked all my settings and such, could it be alpha map related?
(the tennis racket looking thing, see that the texture applies over it)