My best buddy is in law enforcement and he recently traded off his Glock for a Springfield XD-M in .40 caliber.
He is pretty happy with it, and it's a nice gun, but he is having a problem finding suitable duty rigs for it.
He would like to find a SERPA type retention rig, but so far, we can't find duty rigs for the M models.
Check pistolgear. I think I remember reading that a Serpa holster for the xd will also fit the xdm. Don't take my word for it but it may be worth making a phone call.
The only duty holster I have found that is made for the xdm 40 is the model 6280 by Safariland and it is a Level II. The Bianchi 7115 for the glock 17 or 22 will fit, but the xdm forces the holster to sit at an angle instead of a straight drop in. The 7115 sits almost like it is made for a woman. The best prices seem to be at: www.opticsplanet.com it may not be a good idea to buy something for the xd.
Pete