I have taken my six week old Tenere off tarmac onto a couple of easy dirt tracks, however I doubt I will use it off tarmac much. I previously owned a BMW R1150GS and a Moto Guzzi Stelvio, both of those bikes were used on a few fairly easy tracks, but my main reason for buying this type of motorcycle is the riding position, luggage carrying capacity and are very pillion friendly.
The fact that they are able to handle various types of road makes their versatility a bonus. On trips to the Alps and Dolomite mountains I have followed curious looking tracks and found old WW1 forts, I would not have ventured down these had I been on a 100% road bike.
In past times for more serious 'off road' riding I used to have a Yamaha XT225 Serow, that was incredibly easy to use, and I wasn't frightened of dropping it and causing expensive damage to it as the other big 'adventure' bikes I had. Some years ago I attended the BMW off road skills course in south Wales and I was totally in awe of the instructors, the way they handled the big 1200 twins was amazing, Simon Pavey was one of my instructors....a true riding god. It also helps if you know you don't have to pick up the tab for any damage.