Hey Chris! Hope the season is treating you well up there!
I did the trip with Tucker and Mik. No way anyone ever motored a canoe up there at any flow. Loads of Class V and VI. But totally doable with a bunch of portages, moderate flows and confidence that you won’t flip: Something I learned on the trip is that a flipped packraft with a heavy backpack in moving water is next to impossible to get to shore while in another packraft. Getting out of my packraft to then swim two packrafts to shore was the only option during one continuous class III-IV section with who knows what around the bend. The other option was waving goodbye to some of the stuff that was going to get us out of the mountains in a comfortable, reasonable way.
The “sea anchor” effect of flipped packrafts with heavy backpacks is another compromise you make when you decide to take a packraft onto a serious river over a hardshell kayak - or even an inflatable kayak. A big, heavy thing tied on top of a floating whitewater craft isn’t good. Rig low is the MO of all river runners. The sea anchor problem can only really be solved if the craft is big enough to tie heavy loads down low - but then you need an inflatable floor so that the floor won’t rip, and you are looking at something more like an inflatable kayak and a lot more weight. So there are loads of choices…hopefully there is a really compelling reason to take a packraft. In our case, the long hike in merited it.
I’d consider a fight onto the Coffee Glacier with a hardshell kayak (or IK) next time. The lower gorge was a long beautiful Class V section which would be great for a kayaker and frustrating and dangerous in a packraft. Portages would be a bit tougher, but there would be fewer, and there would be less equipment as we used in the travel from the Ruth to the terminus of the Coffee.
Here’s a trip report of packrafting the Coffee River of the Alaska Range. Cheers!