At most flows that stretch is II-III-. For fishable flows you'll mainly be dodging rocks. There aren't any dangerous/retentive holes, ledges, or undercuts. That stretch gets its "reputations" from fisherman taking drift boats down and getting hung up in the rocks and sinking them. I personally know one person who did this.
If you can read water, and know how to pick a line through rock gardens, this sections is of little concern. If you don't get these concepts, the run is still manageable - you'll just want to plan a little extra time for scouting.
Obviously one of the big things to remember with the NP is that it's very secluded. If you get into trouble on the upper sections, there is a good chance you won't see anyone to help you out of your pickle.