man that reply was quick!!
funnily enough, i've just got myself a gear diff with the intention of trying to fit it in the front.......not as easy as it sounds!
the main problem i have with a spool is waaaayyy too much steering, then the back end losing traction out of the corner until the front finally pulls it straight.
ive got a testing session in a couple of weeks at an indoor carpet track that is known for having loads of traction, last time i went i couldnt get rid of enough steering until i turned my steering rates down to 70%!
the idea of a gear diff with really heavy oil sounds like a solution, as like you said it potentially will give the best of both worlds!
have you seen a gear diff i the front? if so, how did it go?