After completing this trip I am surprised that it isn't vastly more popular.  While it is true that we did it in a veritable sprint it still wasn't excruciating.  Add 4 or 5 more days and even in the low flows of September it would be a very relaxing trip by most people's standards.

Day 1
7 miles.
We pushed away from Boundary about 4PM and floated to Trail Flat arriving about 5:30PM.  We shared the camp with some back packers who were glad to get the beer we brought along, not to mention the fire in the fire pan.