Just thought I'd put in my $.02. I presently own three XD45s, two with 4" barrels and one with a 5" barrel. I have been using the Blackhawk Serpa (two of them) for several years now. Since they both came with a paddle AND a belt attaching system, that's how I run them (one of each). Since they are identical and the weapon is retained by the trigger guard, all of my weapons work in them including the 5". It has been several years since I purchased these holsters and I don't remember where I bought them (could have been Natchess Supply) but I do remember that I had to specifically seek out a model for the .45 frame as it was different in size than the 9mm. They both work great.
Wish I could be of more help, good luck in your search.