I dunno what the hell the problem is with thumb safeties-the 1911 has answered that question about as thoroughly as it ever can be.
I had the opportunity to shoot the XDM yesterday, rather unexpectedly, and I must say it was at least an interesting experience.
The first thing that I noticed is that they've redesigned the cases. According to SAI, the standard pistol cases that XDs and their 1911s have shipped in are actually relabeled power tool cases. The new boxes are stackable (that noise you hear is the sound of distributors and dealers nationwide sighing in relief) but the pseudo-rails on the sides are utterly baffling (the case won't open if something's attached to the rail).
One of my biggest complaints with the original XDs has been their abysmal aesthetics and mediocre ergonomics. I'm willing to grant that the XDM is indeed better on both counts, although the frontstrap patterning really could use some light sanding to improve comfort. Overall, in person the XDM bears an almost suspicious resemblance to the CZ-100 series in both slide configuration and frame styling.
My first three rounds at 50 yards hit about a foot above point-of-aim, on the right side of the target. Center-to-center the group measured no more than 3 inches. I'm going to attribute that more to luck than anything else, as the subsequent nine shots were distributed in an arc along the upper right side of the silhouette. The "match-grade barrel" may indeed be of superior quality, but the difference will scarcely matter with such a rough and creepy trigger pull. That may smooth in some over time, but the difference in feel between the new XDM and an old XD9 with thousands of rounds through it was quite noticeable.
On the plus side, the new ambidextrous magazine release actually works fairly well for me, which I found to be a pleasant surprise. As a southpaw, I've found that most ambi releases are more difficult to use than a traditional 1911-style left-side release. The XDM breaks from tradition in this respect, with a smooth, functional ambidextrous release that's easy to activate from either side. It's too bad that they didn't see fit to do the same for the slide release, and make the pistol functionally symmetrical.
On a final note, all of the safety nazis out there will be pleased to hear that the XDM does not require the trigger to be pulled in order to remove the slide from the frame. Field-stripping is just as fast and simple as breaking down a SIG.