100K is not as bad as it sounds. For offroad bashing on very loose surfaces its fantastic. Some of the hill climbs i've manged to do i initially thought would be impossible. You just need to slow down a tad more than normal to turn
The majority of diff fluid discussions i see these days ppl are using 50K front and 30K rear. I've gone with 50K front and rear on my new build but yet to try it out offroad.