Like LT and TXI noted, the grip angle on the XD is more familiar to 1911 shooters. I can swap between my 1911s and XDs without any real adjustment. I have three XDs: a stock XD9 Tactical, a custom XD9 Tactical, and a stock XD45 Service, just like yours. I've only shot a few brands of commercial ammo through 'em, but with about 5,000 rounds among 'em there's never been a malfunction, and the custom XD9 is one of the most accurate handguns I own.
For defensive purposes, I admittedly prefer the .45. Just my choice. My primary carry is a compact 1911, and my primary home-defense pistol is the XD45 Service.
I shoot Glocks, too (heya, Jason!), but it takes me about five or ten minutes minutes of dryfire to get the point-of-aim on the different grip angle. I never warmed up to the .45 GAP, but I might be tempted to try the Glock 21SF.
The gov'ment may not have continued with the "Joint Combat Pistol" spec, but I think we ended up with several great .45 ACP pistols as a result. That spec, BTW, called for a 1913-type rail and, among other requirements, a grip size that "shall be operable for a range of operators from the 5th to 95th percentile per section 3.6.3."...meaning small hands to big hands. The previous .45 ACP double-stacks eliminated small hands, and challenged medium-sized hands.
Manufacturers may be none too pleased by the government's cancellation of the spec. It meant hundreds of thousands of units in guaranteed sales, plus the huge civilian marketing value of being selected THE new military sidearm.
But we get to reap the benefit of all the effort to meet that abandoned spec. It wasn't was an inferior specification; I think cost (first) and politics (second) killed it.
You and I, though, get to buy reasonably-priced, high-cap, quality handguns in good ol' .45 ACP.
We live in great times, don't we?
