That photo of a rocky trail looks more advanced than anything I'd want to ride. DH and I attempted to ride one trail that looked like that, and even he fell. He is not really a MTBer but is braver than I -- I stopped and walked before I fell. We didn't make it far before we both decided it was above our ability and turned around. Just not into a lot of rocks or roots.

When I first started MTBing and was riding my hardtail, I rode with a couple of friends on some twisty trails that were rated beginner to intermediate, and I found them really rooty/slippery and difficult in places. Lots of switchbacks too. That was when I took a few falls and ultimately decided that I would stick to easier stuff. If I'd had the time and desire, I could have taken some clinics and learned to ride that kind of stuff, I'm sure, but I didn't. I was working and didn't have extra time to spare, and at the time DH didn't have a MTB and had no interest in it, and I wanted to continue spending time riding on the road with him.

So, like Crankin, I am a bit of a MTB dropout, but that doesn't mean I don't like my MTB! I just enjoy road riding too much to spend the time to improve my MTB skills.

That said, I've found that my MTB is awesome on rutted, potholed urban roads as well as the "lighter" gravel roads and trails we ride. We have used them riding packed trails like the Katy, Michelson, and Virginia Creeper, finding them far more comfortable and forgiving for those unpaved surfaces than any road bike would be.