Moving the weight more forward with also reduce the amount of weight transfer to the front during corner entry. This is a bit counter intuitive, but when there is more weight on the front to start with, there is less to transfer to the front.
So moving the bats forward is like running more positive rear droop.
Personally I have the batts all the way back, with about 1.5 mm droop using the "hold the tires down and lift the chassis" method. (about page 179 or so has a description)
I find that it is very sensitive to droop changes - I may move one side up one or two slots to see what it does. Then again I might just add a bit more rear toe to reduce the corner entry twitchyness.
I also haven't tried to move the rear wheels all the way back yet. Probably the easiest to change so I think I'll try this next.
Sorry - just thinking as I'm writing.