I have the XD SC40. Nice pistol, and it shoots fine, though I am thinking about getting a Sig 239 instead. There's nothing wrong with the SA at all, just a question of personal preference.
The XD Subcompact conceals fine, and is roughly the same dimensions as many of the other 40's. The short grip, much like the Glock 27, isn't a problem to shoot unless you are doing hundreds of rounds at the range.