Coach L,
I tend to agree with bbscout on this one. The fence drill is kind of high maintenance. There are benefits if performed properly, but the kids, especially the younger ones, find creative ways to miss the fence other than a proper swing if you don't watch them very carefully.
As far as the hands/knob to the ball IMO, the key is for the knob to be pointed in the general direction of the anticipated contact point when the elbow drops into the slot, as that will result in a short swing, but that trying to pull the knob to the ball with the hands can also lead to problems with some kids.
As far as Epstein goes, I think you have to buy into his program pretty completely and be willing to put up with the kids going backwards for a little bit before they make a jump forward.