I have the XD compact. It has a service length slide and width, but the grip is trimmed about an inch shorter than normal. Basically that the inch of the butt that normally causes printing. It also has the option of full length mags so you essentially have service and compact model in one. I tend to carry at home, and nobody has ever spotted it. My wife doesn't even know if I'm carrying unless she hugs me. Other bonus is since it is effectively service sized when holding it, you get the accuracy and controlability that goes with it. That said, double stack is double stack. They weigh enough that you need the spare mags just to balance the weight, you have to have baggy shirts, and appendix carry just doesn't seem to work well with them.
I'd like to have one more handgun in the single stack compact variety and the XDS got some pretty awesome reviews. If it ever gets into CA, or I ever get out, I'll probably get one. Otherwise, I will probably settle for one of the single stack 9mm varieties.