I have the XD 45 with a 5 inch barrel. it was $450.00 at academy. paid an extra $75.00 for a good trigger job. I doubt the XDM is going to shoot much better. I say buy the XD, and get a trigger job. If you find you can shoot better than the gun, have a competant gunsmith install a real match barrel. That is what most of the competitive shooters are doing in my area.
If after that you still want more accuracy, build a custom 1911, those things are still tops for accuracy once a full blown wad of cash is throwed at them.
for me the idea behind the XD was how good can I get it for cheap as possible. If you can score a used one with a good trigger job already done, all the better!