There are a number of good options out there. I recommend the Crossbreed Supertuck as one of the best IWB holsters.
From my experience a full size XDM .45 is a little big to carry IWB. I would suggest looking at a OWB holster like an Askins style which holds the gun tight to your body and can be concealed with a shirt or coat.
Excuse my ignorance when it comes to holsters as I have only carried in my glove box, but with the wood backboard of the crossbreed that forces you to wear on your back, correct? How does it feel sitting down?
The crossbreed holsters are made with leather and kydex. Where did you get the idea that they are wood. I carry a full size 1911 in a super tuck and am very comfortable with it.
I carry my M&P Shield in a $7 Blackhawk IWB holster. It fits like a glove, I can draw quickly without yanking the holster too, and I can remove the holster and gun easily if necessary.
I've been looking at some of the Comp-Tac holsters lately.
for the Supertuck. Mine holds an XD45.