Springfield XD is a great pistol all the way around. I have shot the XD 40 Sub-compact, and it is a great shooter. But being a double stack mag made it a little thick for 100% comfortable CC. Especially when compared to my PF9. I assume the dimensions of the XD 9 SC is similar to the 40. The XD may only be an inch thick but it is "blocky". When you want to CC when wearing a pair of shorts and t-shirt, and are of relatively thin build, every fraction of an inch counts.
If you go Kahr, I would stay away from some of the polymers. Nice guns, but a couple of gunsmiths I respect have told me they are seeing some durability issues. Not knockin them though, and if I had the funds, I would've probably bought a Kahr when I was looking for my first carry gun.