Although I don't carry a 1911, for me, concealment and comfort are both big deals.
Unless I'm out to dinner or going to some other kind of event where I must "dress like an adult," I'm usually in an untucked T-shirt, and I prefer to have leather against my own exposed skin.
The XDm's magazine is large and bulky - especially when I use the full-size magazine grip extension with my Compact - but I carry it really comfortably in a Comp-Tac MTAC IWB magazine pouch. The extra leather over the top makes all the difference.
Sure, it's not a speed rig, but the need to reload (on a pistol that's already 13+1) isn't my true priority for carrying the spare mag: it's more the fear of malfunctions...and for that, I'd either already be bleeding out on the ground, or else should have high-tail'ed it to some kind of cover to work the problem.
Certainly, any day where I'd have to draw my concealed handgun would be a bad, bad day...but the day that I'd actually need the ammo count of my spare mag? that's probably going to be the Zombie Apocalypse - so I bias it towards concealment and comfort.