I've done a portion of Red River Gorge that's called "Hillbilly Triangle"
It's located at the base of Appalachian Mountain, so there are a lot of twists and turns inside a forest. My riding buddy said it was as hard as The Gap (I haven't been to the gap, so I have no comparison)
Unfortunately, the road condition was bad sometimes. Lots of gravels in the middle of the road.
http://www.kytwisted.com/forums/index.php?app=core&module=attach§ion=attach&attach_id=262
I will post pictures for this trip one day