I'm in a similar situation with my 2006 S8. I've taken a look inside my manifold with a borescope and the runner flaps are in a state of disarray, with two or three hanging down, along with the linkage between the two banks dangling attached at only one end, and the drive from the actuator is broken too so presumably they never move. This is no surprise as I have it on good authority that the manifold hasn't been taken off in the last 100,000 miles, and may well be the original with 173,000 miles on it now
In theory I shouldn't be able to sleep at night, but I haven't been able to find a story about flap problems actually damaging the engine. A few stories of bits of plastic being found on top of valves after people go looking for the cause of misfires, but no catastrophes. The only true disaster story I've found is this one, where the engine didn't survive a new manifold:
https://www.pistonheads.com/gassing/...&t=1586386&i=0
So I'm two minds about the risks of fixing it against the risks of leaving things alone, as the car gets me to the shops and back just fine
Still, if I could take advantage of your searching around, did VRS say they were happy to do the whole job? I get the feeling I should probably take care of things.