Norman
It aint so much take-off that's the problem, although I'd contest you being able to get a fully loaded Q-400 out of there with fuel and sufficient reserves for AMS as an example, it's the landing distance.
Factor for a wet runway and you've just had it - and it does rain quite a lot up here. Even on a dry runway, you are not going to land with sensible 'minimum' reserves and a full passenger load.
I'd still like to see a list of those airliner types people think could both take-off and land there with a good 80% load factor say, and enough fuel when outbound for perhaps 300-400 miles or so.
On the topic of business jet access the straight-wing Citations and the Falcon 50 have the very best landing performance of all jets and would indeed get in (only just - a great number of pilots would dismiss it out of hand), but strictly on a private basis, never public transport/commercial/charter/air-taxi etc.
The amount of GA and Biz Av traffic one could see going through there would never, ever sustain the costs of running the place and, again, commercial ops are simply not viable with that runway length. Far too constraining.