Nice pics and article, anony.
I did the Upper Upper Salt in the late 80's (hope the tribe has a statute of limitations), low flow (about 425 I think), in a 10 foot conventional floor raft. Probably the single best day I've had on a river. We also did 3 portages...and there was a 4th we probably should have.
It was both pushy and creeky at that level. I recall making a mental note not to ever take a raft in there at much higher flows as the portage of Wet Dream (that's what we called the biggest drop) would have been damn near impossible. It was a vertical 30 feet at that level, but I imagine the anonymous paddlers saw more of a double decker bus eating size hole. Doesn't get wider, just deeper. I've hiked down to that thing at 10k+, it's a sight to see!