Another surprisingly difficult thing for me, and I'm sure the survey teams will run into this as well, is to go into the damage assessment without preconceived notions. You can't go in thinking EF5 otherwise you will naturally search for indicators that prove it correct, while ignoring those that suggest otherwise. I never ran into tornadoes anywhere close to this intense, but it was often an issue with tornado vs. straight line wind.
These survey teams will have to mentally prepare themselves to be completely objective, despite the devastation laid out before them. I don't envy their position at all, because as much as I would want to be on the team I don't know how I would handle it. The EF2 in Putnam Co., Illinois on 6/5/10 was enough to shake me (being my first significant tornado damage).