I joined my "heavy" friends in big rafts and inflatable kayaks to run this 44 mile section in June (I was in a Yukon Yak with my gear in an Arctic pack on the bow). My goal was to get more class III experience and that was definitely achieved!
There was some question whether the Rangers would permit my packraft (craft must have three chambers and be made for whitewater). I rented an IK as backup but then got the go ahead blessing at the put in. I think it helped when I mentioned that Roman had gotten a permit for the Grand Canyon recently :)
Gradient avg of 13 ft/mile. The first half levels were around 1350 cfs. After the Yampa joined in, level was 10,000 cfs.
We paddled, 6, 10, 10, and 18 miles with day 3 mostly flat water. The river was wide for the most part but did have some narrow rocky sections. One of which was Upper Disaster Falls where I swam for my first time after the stern dropped over the edge of a hole. I let go of my Aqua Bound Manta Ray paddle and lost it. There were plenty of people pulled over and watching but no one saw the paddle. After that folks with all black paddles put some neon orange tape on theirs to make them easier to see. I made a note to do some more practice falling out and hanging on to the paddle :)
The water was bigger, holes and rocks more frequent than on the Desolation/Gray section of the Green I did in April.
The two toughest rapids were Hell's Half Mile (day 2) and Moonshine (day 4). Both of these are rated Class III by most sources (one source rated this section of river as a class IV) but looking at Roman's rating system:
http://www.backpackinglight.com/cgi-bin ... ystem.html
I'd call these PR4 or PR5. I made it through both, although how I didn't flip in Moonshine I don't know. I went into a huge hole in Moonshine, got turned 180, sat on the down river edge of the hole for a second and luckily got spit out.
Otherwise the paddling was pretty straight forward - avoiding rocks in often large waves but with room to maneuver. The wave trains were less regular than on Deso/Gray and the boat got shoved around a lot in them, often with refreshing buckets of water in the face :)
The scenery was spectacular with some fun side hikes at our camps. We saw a lot of mountain goats who didn't seem to mind us. The water temp was a very comfortable 60 degrees.
From the regulations (no self supported kayak trips allowed), it might be a tough nut to crack to do an all packraft trip on the river. It was a blast doing it with "regular" boats though!