My impression, at 800cfs, it was all class III with Powerline as a III+. Powerline is a very steep, if short, drop. You cannot see over the horizon line until you are committed, there are some ugly rocks on the sides but the center is flushy. Chunderboy ran the whole rapid upside down, as usual...
It is interesting that the canyon walls are much steeper in the lower box than the upper box. If you lost your boat in the upper you could get creative and probably manage to scramble out, but the cliffs in the lower box are bigger and continuous for miles. I guess that's why the lower box attracts all the suicides, you can really
launch your car and probably get like 5 to 10 seconds of air time. It was wild seeing the mangled remains of cars here and there.