I used the Bob Ibex suspension trailer with an older, rigid mountain bike.
It works great on singletrack provided the trail is non-technical, free from deadfall and you don't have steep hills to climb. Pushing your bike and loaded trailer up steep hills is brutal.
For something like the Colorado Trail. I'd be inclined to go ultra-light (without trailer).
IMO the best off-road application for using a trailer is on rails to trails and unimproved gated forest service access doubletrack. The limited grade change makes this much more enjoyable.
When you intersect with singletrack, it's much more fun to unhook the trailer, and do an out and back without all the extra weight.