Elmo - I don't think A/B is an option. (1) it could be problematical as the nozzle is adjusted to let the LP turbine drive the lift-fan, and the engine fan stream is diverted to the roll posts. (2) The main nozzle gets tilted slightly down during the deck run, to offset the lift-fan's nose-up pitching moment enough to keep weight on the nosewheel. A/B would therefore result in something like this:
