Danielle, actually I had a 5d2 from the time they came out until a few months ago. I was doing some 2nd shooting for a wedding photographer and I was the unit photographer for my guard unit for a few years. I have since quit doing both and really had too much camera and not enough time to shoot. I was also somewhat lens-poor.
The guy I used to second shoot for offered me a really good price for my 5d2, just before the 5d3 came out, so I took it. I used the money to buy a T3i, a 200mm prime, a bag, and a tripod.
For sure there's some things I miss about the 5d2. It felt way better in my hands and had a little more dynamic range. On the wide end, it was great to have a full frame, and I liked the ISO capabilities.
Fllip side though, the T3i is incredible for the money. Focuses very quickly and accurately, faster than the 5d2 in my opinion. The screen looks better, and the articulation is awesome - especially for video. The last Rebel I had was the 350d and Canon has come a long, long way since then. Until I either start making money with a camera again or strike it rich, the Rebel paired with fast primes is good enough for me.