Curious about this as well. I've got an XD .45 acp Tactical (bitone with the thumb safeties) on the way here.
I'd like to shoot it some to find out if it's worth putting an RMR on.
If it is, get the slide milled for the RMR (find out if the RMR will fit in front of the present rear sight or if a new slot for a rear sight will have to be milled between the RMR and the loaded chamber indicator).
Get the RMR on it, shoot it some more and decide if it's worth putting one of the Power River triggers in.
Could be a sweet cold weather carry pistol for outside the house/garage/woods pistol (open carry).
I have two XDM's now. A 5.25" 9MM (not worth the money I paid for it) and the 3.8" 9MM (sweet shooting little pistol that made the 5.25 look like a Glock) that my wife confiscated a few years back.