I guess the question of how much drive/Usefulness can we expect from the vc has evolved from the handling characteristics of an 80 on slippery surfaces and whether or not ones VC is functioning correctly. Having tried to drive with a broken drive flange (which I didn't know had broken) only to loose drive a few miles later left me quite puzzled at that time until I subsequently worked out what was happening. So having realised the amount of drive that can be produced by the VC left me wondering why the truck stepped out rather aggressively, as surely the VC should have kept more power going to the front if it was loosing grip at the back. As it is I would rather not have it than be under any false sense of security.
From the above experience, without a front drive flange the truck would go a reasonable distance on the flat but going up hill soon lost drive. Therefore I deduce that the amount of torque transferable is limited and therefore increased loading, RPM, Tyres, gradient do affect its performance based on the driving I have done with it.
If the only apparent failure mode of a VC is total lock-up, Having done several thousand miles with a small radius tyre on one corner, doesn't seem to have caused a failure in my case so I can only assume that it is working. I have already acknowledged the fact that my problem may be unrelated to the VC.
SO all that said am I expecting too much from a VC to give improved handling similar to a CDL rather than just to keep the truck moving forward when surfaces change??