I have 1WD. I can manage fairly rough stuff, and reverse is enough to get me out of trouble. Plus, the rig is lighter, simpler to work on, and perhaps a tad more stable since the sidecar wheel is about two inches forward compared to a 2WD.
If you intend to do serious offroading and really go looking for trouble, then 2WD really shines. If the roughest stuff you tackle is state forest jeep trails and logging tracks, 1WD will suit you.
"You wouldn't be riding a motorcycle if you weren't an optimist."
- Matthew Crawford
2005 Ural Tourist, 2000 Kawasaki W650