I have some thoughts on the laser slippers in general, although no experience with the one specifically for the R-9...
Its an interesting gadget, and I agree that lasers can be an excellent tools on a small weapons like these. I think that the j-frame with a Crimson Trace laser grip may be the highest and best use of the technology.
The problem with the "slipper" design to me is -- how do you carry it? You can't use a pocket holster. Now, I realize it helps disguse the shape, but it doesn't do the other things a pocket holster does -- stabilize the gun in the pocket, protect the finish, and COVER THE TRIGGER. I have said this so many times I am sick of hearing myself say it, but I won't carry a gun in my pocket with an exposed trigger -- any gun, period. So, for me -- this idea doesn't work.