As always, I look forward to seeing the results of your exploration. You do an amazing job of describing and documenting your trips. I always find them fascinating!
Be warned - that trip out of the canyon is brutal. It is about a 2000' climb, and the trail is rather steep in places. I only did it once, but it was TOUGH. You are an elevation animal, so it probably won't slow you down, though. 
Rob Williams said
As always, I look forward to seeing the results of your exploration. You do an amazing job of describing and documenting your trips. I always find them fascinating!
Be warned - that trip out of the canyon is brutal. It is about a 2000' climb, and the trail is rather steep in places. I only did it once, but it was TOUGH. You are an elevation animal, so it probably won't slow you down, though.
Ha! Hey Rob, you know you have a standing invite to join me. On the elevation - it's going to slow me down plenty, of that I have no doubt.
--Paul
I have spent a lot of time on that trail over the years, until the Forest Service trenched Twin Springs Campground (WHY?!!?!!!). Each year I made it down a little further and cleared a bit more.
A couple of years ago, Don and I made it to about 1/2 mile or less to the river. We brushed out and flagged a good portion of the route, although it is very steep and vague. It was never built as a first-class route, and every time I hike it I swear to never do it again "LET IT DIE!", my legs scream. IMO it's one of the worst trails in the district, straight up the mountain for 2 miles, with little tread.
It isn't terribly difficult to follow, but gets into younger growth towards the bottom and hits a very brushy flat. There are a couple of cut out logs, and you should be able to see prodigious loppering on rhodies. The Roaring River canyon is insanely brushy however - a real jungle, so give yourself extra time to tackle that stuff. It varies from fire scarred younger growth to big tangled old growth. Lots of water down there too, streams, marshes, bogs...but nothing you haven't seen before though on your crazy adventures.
Good luck!