Most of my summer riding in the hood, looks like this: Hard pack with an overlay of gravel. A tire like a Shinko actually works better than a semi knobby, at least on the rear. Knobbys made the bike skittish. My theory, more contact area.
Some times you have to much of a good thing, especially if there is a hill involved. Knobbys work better.
They also work better in soft snow
In sticky mud, nothing works well
The point is the bike is capable of it, if you are having problems, it is probably you more than the tires.
I think the bike is designed for a stand up rider in order to weigh the front tire. The front is light 47 vs 53% according to http://www.mcnews.com/mcn/features/2011AugTriBMW.pdf
, more if you are a sit down rider. Various ways to fix that. More preload on the rear, slip the tubes up 1/2" or some combination of both. Irritating, but if you weigh over 185lbs, respring it.
Snowy is right about turns, stock set up and the bike runs wide and the front won't hook up unless you are over the tank. Set up or mods compensate to some extent.
It will not tolerate backing off the throttle in really deep/loose conditions. In sand, silt, and deep gravel it will go where it wants, unless you apply some throttle. Don't grab a fistful, just enough to accelerate. In sand you want to get it up to planing speed. How fast, depends on the type, depth, wet or dry, it differs. The only constant is you need more speed than a lighter bike.
There is merit in learning to ride on a smaller bike, but it still a different skill set involved. It is a tall heavy bike, you not going to horse it around unless your name is Schwarzenegger. There is a relearning curve. Practice, once you have confidence in it, it is quite capable.
I personally don't see enough difference in tire brands to make me any better rider. They either got knobs or they don't. If they do, the ones that have longer knobs more widely spaced hook up better in loose stuff. Maybe that is why I spoon on different ones all the time, searching for that perfect tire.
I think TKC's are a compromise tire. A brand I keep going back to, because if you are truly on adventure, who knows what the terrain will look like?