Anywhere from 6-8 players but none full time.
Example: Martin, Taylor and Arline rotate out at RB but play nearly 100% of time as DB's. Cartwright, WR and Colvin, FB, the same. (Colvin plays LB)
Probably the one player that you might could say plays both ways nearly 100% of the time is Bell (TE and DT)
All in all, pretty sure about 9-10 players see lot's of action on both sides of the ball.