I'm not sure if most people are even aware of the monkeyracing gear diff approach. I've thought about something like that while back, but hadn't tried it until recently. It works, and it works quite well. If you are referring to the oil gear diff, if the diff doesn't leak, I much prefer the oil diffs vs ball diffs for its consistency and very low maintenance.

If you race TCS you might be outside the guidelines so best to check your options. I'm open to any mod since I don't race these days.

I had a few weekends to stop by the local parking lot track to watch or even participate if I had urge, but ended up doing other things. Racing is not a big factor in my RC right now, I just enjoy putting them together, fiddling around with it, and just driving them around for personal enjoyment.