"I've seen good riders do amazing things on the 990's, but they bought the bikes to ride hard and were willing to pay the price."
This statement well sums up riding ANY of the big ADV bikes on or off road. If one is a very competent rider, rides hard, and is willing to pay the price, both in personal injury and damage to the bike, then just about any of the big ADV bikes can be handled like a pro on or off road.
Dare I say for the majority of us mere mortals it is in the skill and physical conditioning department that holds us to lower levels of perfection when riding the big guys, especially off road.
A great rider willing to pay the price of replacing machinery more frequently than the guy who wants to get 50-100,000 miles out of his ride can ride the humble DL 650 Suzuki quite proficiently off road, and do it far better than one of us lesser skilled and daring members riding a 950/990 or the 800GS.
It's all in the skill, juevos, and budget if the bike is to be ridden hard and treated as disposable.