I kayak. They rate 2 or 3 of the rapids in the first 25 miles as class 5, but they are easy to run, easy to scout, and easy to portage. CRC2 gives pretty good info on where they are, and if I remember correctly they are pretty easy to see from above. Low flows make this a scenic and easy run. Higher flows (I ran it at 4500 or so once) make the run one continuous and large wave train. Not hard, but you have to paddle like hell in certain rapids to avoid the holes.
The bottom 2 miles (all of the Rockwood Box) contains the only true class V in my opinion. Take out at the last railroad bridge, and what I believe is the highest bridge. Get out on the river right bank, hike to the tracks, and scout the whole thing. About 1/4 mile down there is a river wide tree with no portage. At low water it was 6 feet above my head. At high water I had a nine inch gap to squeeze under on the far right. Not a bad idea to scout the takeout either. Then either go or don't, and memorize the lines to save you time and energy in the box. Remember, you are looking down on the river, so that small whole may actually be a large pourover.
The guide book gives pretty good information from what I remember. Plan on a long long day, 27 miles can be pretty taxing.
Kyle McCutchen