Well as ussual I came in late to that shit storm about how the Truss should be rated. I guess the only point I'd add to the mix is that any run a paddler has done more than 10 times (or less) drops a whole class-- for them personally.
Any run other than the most hairy class V++ can be wired by repeated runs. This is how the sandbagging gets going. People run something like the Truss or whatever 20 times (or less), and lose sight of how difficult it may have been the first time down. Even having someone give you verbal instruction, if you're willing to follow without scouting, shaves off some of the difficulty. I consider the rigors of scouting and portaging part of the rigors of completing the run. It consumes time and energy, and doesn't ensure you won't get hurt on the side of the river climbing over something, ect.
The rating system is designed to give people who've never been there a way (however imperfect) to asssess the difficulties their likely to encounter. Debates around this issue are natural, and eternal.I find Bennet's book to be consistantly rated, and I read it with the understanding that skills and equipement do advance, and popular contemporary assessments of the ratings with it, however slightly. We need a grounded metric that everyone agrees on, and the Bennet book is it, along with AW. Without these authorities, we're all just talking smack.
The bottom line is, IMHO, paddlers should not go poking their bows into canyons unless they've done the proper research (abundantly easy these days with the internet) about what lies downstream. I believe a paddler should have a BUFFER ZONE: an EXCESS of skill required to complete the run they are doing, ideally. Or at least the reasonable skill levels required to make it down in a controled and calm way. Because you never know what may go wrong.