I shoot SWC in both my XDM's(40 & 45),I have no issuse with them.They feed just as reliable as all my other guns.They both are new pistols (I bought both this spring), the 45 has the hump, but the 40 doesn't. I don't notice a difference in feeding though.
As far as accuracy ,both of mine are the best shooters,real easy to reload for and get outstanding accuracy and the bores are as smooth and crisp rifling as some of my aftermarket barrels , the chambers are on the tight side (the 45 is tighter than the 40). I did put PRP trigger kits in both because I'm one of those shaky hands type people so I needed triggers that are light as possible and crisp.
If you question whether it is the gun or human,try to shoot several guns out of a rest,with several different loads and take the human out of the equasion.
Bottom line is I will always own a XDM or two or three or four or five....