I think the Jamboree's are great for those that want to go and meet new people and/or are maybe afraid to get out there in the wilds all alone. But for sure you would want to be on four wheels to enjoy yourself- four wheel rides are way to slow to be enjoyable if you are on a two wheeler.
One has to be careful enough (and always remain respectful) of other users) when there is almost no-one on the trails- like in June. To be courteous and safe during a Jamboree and still run fast enough to have fun is simply not possible.
Nayther- make time to do a UT trip. The whole place is easy to navigate and not to be missed!