I put a pair of Continental Race King Racesport 2.2's on my drop bar bike at the weekend and I was blown away by them. Very light, the bike is stupidly quick on tarmac and they are great on light trails. I rode it hard on a variety of surfaces - hard pack gravel, loose small stone gravel, dry dirt tracks, tow paths and woodland trails and they are as good as they say.
I wouldn't expect them to do as well on rougher more technical terrain or in soft mud, but they are definitely the best tyres I've used that are just as good on the road or 'gravel'.