This is not a dig against the holster. I happen to love the holster, but it does have one issue and I can't believe I haven't figured this out yet.
On the XD and XDm series of pistols there is a grip safety. This is a necessary design since unlike other striker fired pistols the XD line cocks the striker on recoil and keeps it in tension until the trigger is pulled. The striker is blocked by the grip safety and you have the added safety on the trigger. A Glock actually pulls the striker back on the trigger stroke and releases it. Therefore a Glock striker is at rest until the trigger is pulled back. I really have no comments on which is better because I like them both.
The problem with the holster lies in the fact that it's retention strap compresses the grip safety and that leaves very little holding the seer in place. Since I wear the holster in pretty aggressive uses such as ATV riding and snowmachining it has become a real concern.
Just something to watch out for on XD pistols and 1911's with grip safeties. On a side note, I wrecked my wheeler a couple years ago with this holster and pistol with no ill effects..at 40mph. Still not a good practice and I will be looking for a solution.