I've since bought a Comp-Tac Minotaur and the problem has been solved. The adjust-ability on that holster is great and now I can pretty much wear anything I want and the bulge of the gun is hardly noticeable. So if you insist on an XD, which is pretty much as wide as my Glock, I'd suggest the Minotaur or the Crossbreed holster. And don't forget a dedicated gun belt. That's probably even more important.
If you haven't purchased a weapon, though, I'd highly recommend going with a 1911. They're soooo thin and easy to conceal. I love shooting them, and I've decided to eventually move over to a 4" 1911. I love my Glock, but the 1911 is just a sexy piece of hardware.
