G'day Ozscott,
I've got the twin diff locks and gotta say that I've driven on a lot of types of tracks and surfaces (rock, sand, snow) and the biggest single gain was fitment of CDL when compared to totally unlocked DII.
After that, the benefits of twin difflocks are there, but it's not as huge a gain anymore. I've been able to drive up the same difficult tracks multiple times whilst experimenting with CDL, ETC and diff locks. The ETC is hard on the planetary gears on the diff centers because it is pulsing the brakes which is sending shocks through to the little spider gears. This led to the early demise of my factory diff centres, hence I fitted the ARB diff locks, because they are essentially a stronger diff centre, even when unlocked.
Also, I have found ETC not very good in sand.
Lawrance

