Same holster works for both models. I use the Galco king tuk made for the xd and it holds my 3 xdm's just fine. I also have a Blackhawk Serpa holster and it works well also.
The only thing that really changed in the xdm line was capacity and match parts. Capacity upgrade for 9mm and .40 unchanged capacity for.45.
"The spirit of resistance to government is so valuable on certain occasions that I wish it to be always kept alive. It will often be exercised when wrong, but better so than not to be exercised at all." ~Thomas Jefferson