I don't really consider a FF camera as an "upgrade" to a crop sensor DSLR. They are different and can compliment each other. I like having 2 bodies with 2 different crop factors. Gives me a lot of options for focal lengths, pixel densities & DOF control.
I had a 7D first, then added a 5Dii. My opinion is that the 7D is a better "camera" in every way EXCEPT IMAGE QUALITY. And that is obviously a big deal.
I love that my 7D has a built-in wireless flash commander, more custom control s, built-in levels, Grid in viewfinder, faster FPS, more focus points, better Ai-Servo, a dedicated movie button...
I love that my 5Dii has a FF sensor, less noise, changeable focusing screens...