There's an article about the Quadrasteer 2500 Suburban in the Jan/Feb issue of Truck Trend. Right now it only comes with the 6L gas engine, and for that reason, the article mentioned the "biggest fault...lack of power". This was based on taking a 6800# boat/trailer up a 5% hill in Los Angeles. Other than that, it had a lot of positive comments. [add - another reason may be the 3.42 axle ratio - per the spec page... based on that, there's no way for it to have a 12,000# towing capacity]
Priced out one... close to $50k.
I drove a PU that had it... turned great. Still waiting for retirement to purchase something. Good luck with yours!