I like the XDM...but not for a carry piece. A friend has one and it does shoot nicely, but I just don't see carrying one around daily. Maybe it's my physique, but I just don't think I could comfortably conceal anything much larger than my XDs for daily use.
Haha I used to think that about my Ruger LCP - how would I conceal something bigger comfortably, being a late-middle-aged guy with a gut? I found that the XDM Compact (3.8" with shortened grip and flush 13 round mag) actually conceals very well and comfortably at about 4 o'clock using a Crossbreed Supertuck holster. I just have to loosen my belt one notch from its regular position. My issue with the new XDM Elite is that there is no option with the shortened grip, and that is the hardest part to conceal, to me, whether your shirt is tucked or untucked. The extra inch or so in the grip makes a lot more difference than you would think.
You are right in that if 7+1 isn't enough, will 13+1 or 19+1 be enough? Most of us will never end up in a gun fight or shootout, and on average, if 2-3 rounds don't resolve the situation, you are probably in trouble. I read that type reasoning from XDMan a while back, and I've almost stopped carrying my spare 19 round magazine, which makes for one less thing to conceal.