Jamie2k9;
I usually tend to agree with your analysis but on this occasion I differ. If KLM can do night stop and therefor offering a business solution for the Belfast Based Traveller with an early take off from Belfast and return say in the evening say to arrive about 730 that would work, putting say F28 on the route would address the capacity need.
Also the flight in on Friday night could go straight back to AMS and offer an evening flight to the leisure weekend traveller, no service on Saturday and 2 on Sunday evening one night stop for Monday early departure and the other to addres the weekend leisure traveller. These options ie early out late back business orientated schedule would satisfy the connectivity at the hub at AMS.
This would be my vision of the most effective solution for all parties concerned. Hence my contention that KLM are best placed airline to serve the route.
EI-BUD
Surely this would mean massive hotel costs for the crews who would operate the flights as you suggest them? Would make it kinda hard to make money from an already well catered for route?