Okay, so on my M05 I took out the ball diff and using the factory bevel gear diff with Tamiya's ceramic oil which is thicker than the normal grease yet thinner than AW grease.

As far as I can tell, the loose ball diff setting was able to take corners tighter than the bevel diff at higher throttle, but then it could've just be that the ball diff was loosing (or slipping) energy due to the loose clamping of the diff itself. I can get the same entry and exit cornering angles using the bevel diff just as long as I go easy on the throttle. Overall lap time is the same.

In conclusion, on my tight and soso traction basement track, the bevel diff does just fine. I might as go as far as saying I recommend the bevel diff in this situation because you won't need to worry about opening up the gearbox to re-tighten the diff.

I am keeping my V2 balldiff though. I like to have different flavors.