For the most part, things have been summed up. But, not all. Not all XDMs come with fiber optic sights. At least the wife's didnt, new. Its a 3.8 9mm. Now, the XDM 3.8 does come with the interchangable backstraps, match this and that, but also in a short grip or long grip. Oddly, the short grip was $60 higher. Less material, higher cost. Short grip fits the 13rnd mag, and has mag sleeves for the 19rnd mag, giving it the full size grip.
And it doesnt outshoot my Glocks. (17 and 2 19s) But it does shoot nice.