Different crafts, different captains, different mindsets.
I've been running the J/B since 1986. The first time we ran it it was 2700 on the Hot Springs gage, self support kayaks only. Guidebooks of the time said "not recommended above 1500." Jarbidge was small and super fast and fun. Main Bruneau was huge and fun. We came off thinking we'd never want to run it any lower. There were no rafts on the Main Bruneau run at that level at that time. Subsequently have done it some lower, still an amazingly beautiful place and a fun run. Have run W.F. Bruneau a couple times, too; still trying to get on Sheep Creek (maybe this is the year).
Did J/B again last early May at 2500-2600, knowing what to expect. Upper Jarbidge was swollen, cold, and fast. Not many eddies for rafts, but the run was clean save for the occasional edge-caught snag (no log portages). We did a planned layover day at one of my favorite camps and did a 7hr side-canyon hike. The 'new' portage at Sevy's is a pain in the ass, don't try the left side. Pulling in to scout and most likely portage Jarbidge Falls is still something I never want to do with a raft, but it's pretty painless for kayaks. Everything else was more or less clean. We got to the confluence of the E.Bruneau to camp, and met up with two cat-boaters from OR who had never done the Bruneau. They had put in at the confluence road (something else I would never want to do. That is one nasty road.). 4 other self-supporters pulled up who had done Sheep Creek. All of us were looking forward to the very big water on the Bruneau. It's a blast, if you're ready for it.
The Bruneau at Hot Springs hit 6860cfs on Feb 10 of this year, tied for highest recorded flow (in 1984), with records going back to 1910. That changes everybody's 'remembered database' until some people get in there and report back. You have to imagine some things have changed again.
The choice to R-2 solo has to be based on your own skill set. I'd go super-light, not much more per-person than a self-support kayaker would carry, and be prepared to eddy out and scout or portage fast. Logs are going to be your main concern.
Your big problem is going to be lack of water on the Jarbidge. It's high and cold up there, and all of the current flow is coming from the W.Fork, Sheep Creek, and probably even a fair bit from the E. Fork (it gets kayaked). The Jarbidge is running 46 cfs at the upper gage. It picks up some water at Murphy, but your entire upper run to the W.Fork is going to be scrapy at best.
I have personally come off this run every time thinking, "higher is best," although maybe not 6800. Lower is just slower and bony.
There really is no place to camp below the confluence at the E. Bruneau anymore. Poison Ivy has taken over anything resembling a flat spot. Plan on running all the way to the takeout from the confluence.
It's a spectacular place, well worth the effort. Not sure I'd ever want to raft the Jarbidge, but maybe the R-2 is the perfect rubber choice. Too much time with your butt in the water in IK's. If you go, definitely would love to hear how it went. Hoping to get in to Sheep Creek in the next couple weeks or so, if the water holds.