More questions than answers to this one. If FABs are such a good idea why has the UK not joined Eurocontrol who are the undisputed experts and have decades of experience.?.......perhaps its just a good idea but only for everyone else [typical UK stance ]. It is also a way of moving expensive UK ATCO jobs to a cheaper off-shore provider whilst still enjoying the income stream from some of the world's most expensive route charges.
Ask yourself this: If the UK is so efficient then why are the Nav charges so high? Why do so many aircraft take lengthy doglegs to shorten UK track mileage to a minimum in order to save Nav charge costs......and ask yourself whether this practice has an effect on the Carbon footprint!