Green vs. Vallecito
Yeah, I did the Green once at 100%. I thought the rapids on the Green were huge, but you had a choice to run anything in there. I walked Gorilla and Sunshine and ran everything else, although I would have reconsidered Sunshine after putting in below it. I felt like overall the individual rapids on the Green were steeper, but Vallecito never lets up and you literally can't see the bottom of the rapids, even out of your boat. I paddled the Green with some guys who were training for the Race, so all I got was the beta at the top of each drop and I didn't get to scout much- so it had a similar feel to Vallecito in that respect. Once you get below Trash Can, the rapids drop out of sight and the walls close in. It would be a very bad place to dislocate a shoulder.
As far as I know there aren't any true sieves in Vallecito, but you can easily get pinned in Trash Can and there are more than a few pins spots throughout the run. The cave behind the Entrance Falls has caught a few boats /swimmers as well. I'm certainly no expert- there are guys in Durango that run it 4 times a week, all the way up to 2.4', and they could give a better report of various levels.
That being said, if you've paddled the Green I'm sure that Vallecito is within your ability, but I would definitely go down with a guide. And I wouldn't want to be the first one down in the season- my friend Jim put his chest through a 4" thick log across the creek once a few years ago as he came barrelling through a rock garden- luckily it broke.
You can somewhat scout the creek from the high trail, but you're still 60-70' above the water, so it's hard to get a sense of how steep it is from up high, and because it's so boxed in you can't see all of the rapids anyway. Gary E, Rasta, Gordon and Rolf took me down the first time and I was glad to have a wealth of beta getting down there.