I'm happy to ride as sweeper on either hard or easy routes, pull folk out the trees, rescue bikes that sort of thing.
Might I suggest RobMac, if he is a first aider as he has said, bring his medic kit with him just in case.
I still think the black climb is a very doable and old school choice with great veiws but the red descent from spooky will be the biggest grin factor for the adrenaline junkies.
Not having been to Glentress it is sounding more terrifying with each post added. I have visions of destroyed bikes everywhere and mangled riders wedged up trees.
Best not to ask Velo about his broken collar bone Spooky Woods run then
Actually, I think first timers are likely to get on better due to simply being more cautious on an unknown trail, than folks who know it well and are used to riding it at speed on a modern bike
Note to self...