I have both and I have to say, I don't feel as though I love my 5DmkII as I should.
Reading through some of the points on this thread, I have my own thoughts about FF.
1) "feels like FF" - honestly, I want to say all of the bad things I've seen from lenses is more pronounced in FF (CA, barrel distortion, and vignetting) vs crop. I've been shooting with my 24-105 on the 5D and can't believe how much more correction is needed for vignetting -- maybe it's not that where people get the 'feel' from, but that's what I've seen
2) The iso difference on the 5D rocks hard, probably the best thing about it
3) Never seen banding myself
4) Nice shot for the dog, but if you go back and pick up a rebel, you'll be surprised what you can get out of 'lower end' cameras after you've been shooting a while. I'm still more comfortable with my 60D; these days, (aside from un-cooperative subjects or bystanders) I can't seem to get a bad shot.
5) Auto-Focus speed seems faster to me on the 60D, but I believe Neuro said at one point that it wasn't any faster than the 5D
Lastly, mk3 vs mk2, you're going to see a at BEST $1k difference in the bodies for some time (best price, I mean) . . . until you've shot on FF for a while, you may not see as much improvement for the price difference.
Personally, I've decided to start selling some gear and moving both bodies up a notch, but I have ALWAYS had a bad case of accessoritis and upgraditis. I get sick of cars 9 months into them, but I'm working on that.