I'm in the same situation. I'm RaF boosting teams to 80 and I've started playing my first team ( pally, 4x shaman) in Cata when I get boosting burnout. I've read in some of the other threads that Cata instances are harder to box than MoP so I'm wondering if I'm better off just questing 85 and then doing a combination of questing/instances to 90.

My intention was to start learning how to play my teams in Cata instances so I tried BRC when my team met the iLvL and that didn't go well. Throne of Tides looks to be a nightmare for me. So is worth taking the time to complete Cata instances or just get to 85 and start the instance learning curve in MoP?