Hello,
I am quite happy with the Spec-R Diffs. Only one out of 4 is leaking a little bit.
When there are traction problems, I am hardening the rear oil to approx 1000cst. Last weekend I drove 1000cst with a 5.0 octa, and it felt quite good.
Anyway, I am also waiting for the Tamiya Diffs. I think they will be a little bit earlier available than the revised kits.
See you in Apeldoorn!