SR,
I wouldn't be too concerned unless you are a complete novice on the sticks. Do you float the upper Sky (High bridge to Sultan)? If so you shouldn't have any problems on the lower Hoh. It is one of the easiest floats on the OP, probably second to the lower Bogy. There's a few boulders to miss but log jams and changing side channels are the only real hazard. Having said that, I've never seen the diversion channel except from these pics and don't know for sure how long it will be needed or what its like. In any event this area is easy to scout before you go through. Most river accidents can be prevented by scouting what you're not sure about....and walking/lining the boat past anything beyond your ability...though I doubt that will be necessary here. I'm hoping to make an Oct trip also.