Well hello! Hey, I usually try not to post to much on "which boat is best for me" thread because, naturally, I'm way bias, haha! and the good boaters of the buzz do a great job pointing people in the right direction. But, I did just want to note a few thing.
The Tributary raft line up does use Leafield B7 valves these days, not the Summit II valves that we use on the Trib. kayaks. So, if you do find a used 9.5 out there it will have the B7 valve. (We used the Summit II valves for the first few years on Trib rafts, they were ok on the bigger diameter raft tubes, but not great.)
I also wanted to point out that we have had the Trib 9.5 with a standard floor (bucket boat) out for awhile. So, while you are shopping for a used Trib 9.5, be sure it has the self bailing floor.
The newest generation of 9.5 has a strap in thwart (like the AIRE boats) instead of the knuckle thwart. We had just enough feedback from people wanting to move and add thwarts that we made the upgrade. Not sure what your R2 style is, but having the option to move your thwart is somthing to consider.
I did do a little blog write up about the Trib 9.5SB if you are interested: AIRE Blog: R2ing = Good Foreplay
A used 9.5 might be a little tough to come by as they are still relativity new. That said, we do sell off our demo boats every year...The sale will be posted on our Hot Deals Page this month. (As of right now, I think the outfitter who has our demo 9.5 will be keeping it, but you never know, he might end up sending it back
That is all, good luck in your search for a great little R2 Boat.