Does it *need* a damper? Probably not.
Do you *need* knobbies to ride off road? Probably not.
Do these things help? Sure.
I put the fork mounted HyperPro on my GS a while ago, and it has saved me more than once when I caught a knob on a rut. The bike is also more stable on the road, regardless of what tires I am running. It's really noticeable when I am passing a semi at highway speeds.
07 R1200GSA - 81 R80g/s - 88 Hawk GT - 06 TW200 SuperDuper Tenere