Mechanics

[Theisey]

Just where did you read that (on this forum) about not flagging PI until the play is over?

I've never seen nor heard anything about not doing back-pedling. If doing so causes you to be beaten to the goal line than by all means, don't do it or at least go to a local field to work on it.
I can't think of a downfield college guy I know that does not use the back-pedal during a game. Sure there will be times you have to switch to a side step motion, but for the most part, back-pedal is the common move.