Totti is a fantastic player -- one of the best in the world when his head is in the game but he's not being a fool. That said, he is his own self-destructive worst enemy.
Pizarro sounds like the right choice in place of Perrotta. A lot of the rematch will hinge on how much of ManU's "shallow" bench is needed given the nursing of so many injuries.
But Roma proved last night that they can contain Ronaldo if needed. While he did make some good runs and was the most effective offensive option for ManU, Roma made some great stops that sent Ronaldo running the opposite direction as the ball.

If Ronaldo gets a little more help on the opposite flank, with Roma's questionable D-line, it could spell trouble.
I still give ManU the slight edge in this tie, but it's close and a lot hinges on ManU's health.