We've been rehashing this same discussion for years now.
I currently own a SIG P938 exclusively for when I want to carry off the belt. It's a great little pistol...I think I would just prefer HK's version with a paddle-type magazine release. I would love a single stack version of the P30SK in DA/SA/Safety. I'd buy it in a hot second.
Right now, Kimber has a Micro 9 that is almost the same as the P938 but I haven't even heard of anybody who's bought one yet. I don't know how well the XD-E is selling, but up until now, the P938 has been eating the ENTIRE market segment for a single stack 9mm micro-pistol that has a hammer and a safety. Seems like a very niche market, and maybe it is, but I've lost count of how many of my friends own one. Even my father, who just got his carry permit last week, wants to buy one now. I think HK could could make good money on this, especially with their modular fire control that could allow the same frame to handle DA/SA/Safety, DA/SA/Decocker, and LEM.