Good choice on the XD! You're department will not regret it.
To clear up a few things....
- Although the inner workings are a bit different, the XD is identical to the Glock in real-world operational terms.
- The grip safety is a "disconnect" type safety. It does not block the trigger, rather it functionally disconnects the trigger from the sear block.
- The grip angle on the XD is different from the Glock, so makes for a different "fit" than the Glock. The XD also seems better suited to smaller hands, or big hands with short fingers (like mine).
- The finish on the XD is not as durable as that on a Glock (which is just about as tough as you can get). You WILL need to regularly clean and inspect the weapon for wear, as well as use a good quality protectant as part of your cleaning regimen.
- There are several XD owners (myself included) that have put over 10,000 rounds through their guns with very satisfactory results.
- You CAN legally use XD40 mags in the XD 9 without modification, although you may have to massage the feed lips a bit to make the last round feed properly. Stick with your department's policy to avoid any liability pitfalls for the department.
- DO NOT, UNDER ANY CIRCUMSTANCE, put a round in the chamber and then drop the slide on it. The one-piece extractor is not designed to distend to this degree, and will quickly loose tension resulting in the dreaded Failure To Extract. Trust me, I figured it out the hard way. Always strip a round from the magazine in order to load the gun (which is the proper way to do it, anyway).
- Keep an eye on the front edge of the rail block. Unless you switch to a heavier recoile spring, a steady diet of +p rated ammo will quickly chip away the front of the block. Standard ammo does not seem to cause any trouble (at least not for me).
The XD is an excellent firearm, expecially given the extremely modest price. Count yourself lucky that your department decided to go this route.
Brad