Re the proposed EXT sale issue. I think it's been sort-of said before, but the heavy presence of FlyBe at EXT would be a big turn-off for many potential investors - an airport basically reliant on the fortunes of one carrier, and an airport which is unlikely to get much other airline interest when it's FlyBe's home base.
I do think BRS is entirely different. They've had a conscious strategy of balancing full service/loco/niche carriers - and that strategy has worked well and has allowed the airport to thrive and prosper without any one airline or business model being dominant.