I used to run the long flex plates and the batteries a bit further back, but I also had the servo different up front, and no king pin lub on the front, and 10K in the rear. So I am not really sure if I can compare the setups at all. The more run time I get on this setup the more I can experiement a bit.
I noticed a bit of pitching and excessive chassis roll with the plates in the long config. Where on high bite areas of the track I would get the car to lift a rear wheel and diff out on some tight corners. Stiffening up the damper tubes and going to the short plates with the rest of the changes I made fixed that entirely it seems.