Re:
I use Clement Xplor something or other on the 'cross bike, or Michelin Mud if there's a lot of...... Mud.
The Clements are slick down the middle with knobbly bits on the sides, like Clubby said, you can comfortably ride most stuff on tyres like that, only real sloppy mud etc will leave you wanting more tread.
The Conti Double fighters look like a decent tyre, should roll well but still give grip (especially in corners) off road .
Try your Commuter tyres and see what you think?