Your only problem with the FC-7 and the G70/E80 OS is that FC-7 assignments are global, NOT per UPG. So you really have to think about HOW you want to use it in general, not specifically for one song.
I would MUCH prefer to be able to program it the way I need for each song individually, but so far, no go....
I also worry a lot about putting potentially show-stopping controls at my feet (stop/start, break/mute, accel/rit, etc.), where an inadvertent press could bring a song to it's knees. So I have streamlined my use of it (and cut down on pedal clutter) by using it like this (L to R):
Var 4 (with auto-fill usually ON)
So the FC-7 is the only thing I need carry (other than an Expression pedal). I have to add I do about half our show using LH bass, so this set up really helps me avoid using my LH to press much during the song, but if you are a more standard arranger user, other layouts may work better for you....
An arranger is just a tool. What matters is what you build with it..!