I CC an XDm 9mm everyday. No issues with printing with the right holster.

Both guns are excellent SD (self defense) weapons. However, for me, the geometry of the Glock does not fit my grip geometry.

I have no hesitations on the XDm reliability and quality of the brand. I have taken several tactical and CQB courses with my XDm and have yet to have any issues besides the occasional FTE on a multiple adversary, multiple hit drill in 100+ degree weather.

I tried the .40 XDm and G23, but the "snap" recoil of the .40 (as opposed to a "push" recoil) delayed my target reaquisition time.

The only "1 shot drop" is to the "T" area of the head. That said, for the average shooter, its going to take multiple hits to COM to stop anyone. For myself, my follow up shots are more accurate and quicker with the 9mm vs the .40

Best advice I can give you, like others have said, is to rent both guns, put rounds downrange and choose what feels best for you (assuming you have sound firearm fundamentals).

Good Luck and let us know what you end up with!