Well I had an indoor race last week end on carpet and slippy gym hall floor. Olivier gave me the modified bits on the morning so I could mount them between two rounds. Hey I have the best mate!
I filled them with 10K front and 3K rear. I thought that diff action would be quite slowed with such thick oils, but no, they felt like a slightly tight ball diff on front and a newly-built smooth ceramic ball diff on rear.
You can still feel the hydraulic effect of oil by blipping the throttle while holding one wheel. To me (this is quite subjective though) the held wheel tries to spin harder than it would do with a ball diff.
On track, the tranny felt just fine, but that's a testimony to Olivier's awesome lathe skills. The car was very smooth and not louder by any means. I think that the louder pitch noise from Dex410s comes from the alloy chassis. Traction was very good. The car had a little to much rotation on tight corners, next time I will try with 15K-20K on front.
Is it hard to say if I was quicker with those mods as the race was on a temporary track. My home track is covered by snow by now

so I will have to wait until I can do more tests, but it feels good to know that I can tune diffs as much as I want, from a super-free spinning diff to an almost locked traction machine

And I can use driveshaft boots, yummy!