I'm using it as my base setup for all tracks. But it really depends on how much grip your track has to offer. You'll probably find a track with a lot of grip and 10k in the rear will result in too much of an on-power push. Dropping to 7k might do the trick.

I guess you could treat it as a general rule of thumb - If you find the M1 is snapping or hanging the tail out under acceleration and you've tried everything you can think of too fix it, run 10k in the rear diff