just from my experience.. backing down (correct me if i'm wrong since i don't know what this move is called on defense. but on offense, it is called back down in low post plays) is more effective than pushing the take charge button to take offensive fouls. if you push the take charge button, more often you'll take a defensive foul.
about dunkpacks.. from my experience again, dunkpack value of 9 is so effective. players like tyrus thomas and gilbert arenas can score a lot just by dunking. and it is really hard to block them without fouling. i really don't know if it just so happens that their quickness and dunk rating are in good combination. (as far as i know from nba live 06, dunkpacks are only for aesthetics but i dunno in nba live 07)