I think there is just a point of diminishing returns when trying to put larger calibers in smaller handguns. The obvious first sacrifice is capacity, followed by recoil. (Felt recoil is a subjective element, of course...some feel it more, some don't as much.)

While I personally favor the .45 ACP round, I prefer it in a 1911 (Commander or Full Size), a SIG P220, or a M&P 45 (FS or C.) I have looked at the XDs in a local shop, and it is just too small, IMO. For me, the Shield 9mm is the best concealed carry pistol I have ever had.

For home defense, or for times when I am just carrying in my car and not on me, I still prefer a .45 as mentioned above. However, for the right combination of round and size for a CCW pistol, I think the Shield 9mm is it for me.