Upload & Sell: On
I had a 7D, and a 5D II; I have a 5D III now. My opinion is that your basic idea of switching to full-frame is well justified. When I was trying to sell either the 7D or 5D II to a friend, we did some comparisons, shooting the same subject with the same lens at the same aperture on both cameras. After just a cursory glance at the CR2s, she dismissed the 7D, and it was obvious why; there's just no comparison in IQ. They may be in the same ball park, but not in the same league.
I also have the Tamron 24-70, and it's pretty good, but for times when the flexibility of a zoom isn't paramount, good primes seem a bit better.