I've been shooting with a 60D (my first dSLR) since 2010 or 2011, and am naturally considering going FF. The thing is, everybody asks, "will I benefit from going FF?", and the answer is more likely "yes" -- although it sure depends on the photographer and his/her uses for the camera. What we seldom know is, do these folks who upgraded and now have better gear take better pics now, or is it all the same? For how many of them has upgrading made significant difference?
So I ask you FF shooters: what is it that you can do nowadays with you FF that you would no longer be able to do if you downgraded to crop?
Hope it doesn't sound too crazy -- it makes sense in my mind...
I usually don't reply to only the OP, I generally read through then possibly reply, but this this one I will take a stab at it before reading the other replies!
IMO - Upgrade should generally come when you've hit the limit of whats possible with what you've got. With crop vs FF though, it gets a little trickier. First off though, no amount of new camera will magically make you better! As I am sure many have also said here, you get better by shooting, reading,m refining, trying new things, etc, etc. Also, the benefits of FF are somewhat subjective (IE, if you shoot wildlife, with long lenses - your longest lens will appear to have shrunk on FF. But, if you are shooting in a small studio, you may have hit that wall where none of the focal ranges of your lenses make sense anymore (IE your buying a 35mm because you want a 50, buying a 50 cause you want 85, buying an 85 cause you want 135, and passing on the 135 because its too long on a crop). Low light work is another factor, if you find yourself shooting in lots of tight low light environments, you may find the light sensitivity of a FF sensor much to your liking.
I made the transition from crop to FF in early July of this year. For the work I do, it made sense and I have very much enjoyed the transition. On my 7d, my go to lens was my 24-70. my 70-200 sat in the bag more often than not. And I used the 10-22 quite a bit too. Transition to full frame though ---my 70-200 is now my favorite lens, with my 85mm 1.8 being the second fav and I just snagged a 16-35vII and i am very much liking that lens too!.
To a certain extent, going FF is like grabbing a new lens. I don't know what your lens setup is, but, for me I found that covering the wide end was much more difficult on crop. I liked the 10-22, but found it to be much less flattering than I'd like for people shots.
Not sure if any of that helps.