The main flaw I see with GMC's system is what if you are trying to corner at high speeds? it says the rear wheels steer in the same direction as the front over 40 mph, so it seems to me that would cause some major understeer not to mention a world of other problems.

I thought this too, but that isn't the case. Remember, this is mainly for extended pickups with long beds and crew cabs. I'm involved in the dealer training for maintenance of these things and it is a really overbuilt system. I forget how many times a second the system is working, but it has several dedicated computers for it. And the degree of wheel rotation at speed is very very slight. Only a few degrees. I'm not sure how much info I can give on it, but I'm sure the web would have info.

Basically, it makes one of these super-huge work trucks park like a normal pickup. Great for a work site. It is not a sports car type system.