I would guess it'd be great. I remember visiting (the KY) side of the Cumberland Gap, as a kid, with my parents. I think it's pretty hilly down there, my father was origionally from the far south east part of KY, and as you travel south those hills get bigger. Probably be a challenge, alright.
The one reason I wanted to do the John Muir was that on one map it runs parallel with a river, plenty of water, and plent of fish, when I get tired of rehydrated food.
Thanks Glenn, eithter way, I'll need to do a lot of shorter trips next year, to try to get back in shape to do 8hr leg's of whatever trail I choose.