I don't use the sprint out during the snap, as my kids are only 8,9, and 10.
Yet I really like them to throw while on the run, especially when running to the unbalanced side where we poud them with the sweep, blast and wedge running plays. The defense starts to cheat to stop the sweep, which pulls the safety and linebackers in, and then their cornerback usually stops covering our flanker/wide receiver altogether leaving him wide open.
We scored every game, over the past two seasons, running deep fly route passes that the defense sees as just another single wing sweep they need to stop. I guess thats why we have won and lost in the Alaska State title game the past two seasons!
Just an update... Our middle school team successfully installed a variation of the old TCU Spread. We didn't use it a lot until the the last 2 games of the season, but it definitely has some merit. The person you need to talk to is Ted Seay - find him on Delphi forums Single Wing or 2LD sites.