Is there such a thing as FF nay-sayers? I really doubt it. I think there are FF owners and those who would like to be be FF owners. And the 7D? I used to own one before - its low light performance was really discouraging. I hate to be blunt but the 7d (and the rest of canons line crop line up) sucks and any kind of low light. And those who say they like the 'reach' of the crop sensor cameras, reminds me of the day when people thought that Digital zoom was useful!
Practically it all comes down to whether your uses require more reach than your glass can give you.
If you crop an image shot on full frame you are using "digital zoom". If instead you switch to a good crop sensor, you can get much more detail on the subject.