I shot the one H&H has for rent a couple days after they got it in. I had an XD40 4" and thought that this would be it's replacement.
When I picked it up, it seemed very light for a full size. The slide cutout definately makes a difference. The trigger is exactly the same as the other XDm's, with a reset comparable to a Glock, if not a bit shorter. I'm not the greatest pistol shooter, but I could keep offhand doubles in the center 5" with the target all the way back (25yds, I think) in the first mag. I've never been a thumb's up shooter so the slide lock wasn't an issue. Front FO is very nice, even in dim lane lighting. As said before, this looks to be SA's bid for the top of the production class.
I might still get one, but I'll wait a while. SA's always good about offering a two mag for $25 package once a model's sales slow down. They did with the XDs and later the XDms. The $800 that H&H wants for it is crazy, right around $700 elsewhere. It seems worth it, as an XDm 4.5" 9mm + FO front + rear adjustable + an extra mag would run about the same with .75" less barrel.
I agree with Jesse that SA should ditch the craptastic holsters. I haven't tried the paddle one that comes with the XDm, but if it's anything like the standard XD, it's BS. The mag loader is nice though; those last 3 rounds are a pain in the thumb.