Hi
We have been round Glentress red and blue a few times. We need to take some of the chicken runs on spooky woods ( but not all) and the hairpin turns on the final climb are tricky but possible.
Blue is fine. the jumps on the descent to the hub don't work tho as the wheelbase is so long. Blue freeride is a laugh – and air is possible off the stepdown!
Plenty of stuff in the pentlands
A nice non gnarly route can be done using the pencaitland railway walk Haddinton / longniddry and back along the coast
I have ridden in the lammermuirs but only as a way of getting down to the borders as part of a weekend tour
Gypsey Glen is a nice route and perfectly fine on a tandem