I held out for a OSP 3.8 XDm Elite with full grip but as far as I'm aware it never materialize. (And I know there was the compact but I wanted the full grip, not an extension addition.)
The RM1S is the 'sub-compact' version of the RM1C (compact. It is slim for a sub-compact. I believe that "Micro Compacts" are for pistols 1" width or less. Just my observation.
That was my point. Is the 380 grip the same externally as the 9mm or shorter front to back? If they are the same externally what did they do internally?