I have one and lets just say it is more accurate than i am. I haven't shot the 4 inch in the 45 but i did have the the 4 inch in a 40 and i thought the 45 was more accurate. Keep in mind that is just my opinion and while i can generally hit what I'm shooting at i have a long way to go before i can start comparing accuracy.
As far as a gun to compare it to i wouldn't know were to start. I have always been die hard 1911 and i hate glocks. But i have to say i surprised by the xd-45 its the first polymer gun that gave me a warm fuzzy felling.
I hope that helps and if it doesn't there are alto of guys here that know a lot more than i do that I'm sure will chime in.