TopBunk,
You really need to look at your aircraft's figures.
Again I say that I have not based the situation on fuel alone.
I have done the figures and find that in fuel terms for a certain jet type the extra fuel burnt in making a highspeed descent is 1Lb
How much does 1 pound of Jet A1 cost? Compare that to what you alsone cost per minute and there is a saving in keeping time as short as possible never mind the other cost factors.
So again I say check out the CI in your aircraft and try playing with some figures from the manual.
The point being that how the aircraft is operated is nothing to do with ATC. If operator A wants to try flying slow because fuel is their only major cost then that is perfectly acceptable. If operator B chooses something different then they also are entitled to do that.
The fear is that NATS will loose the run of itself and use it's greener outlook to impose unnecessary restrictions or put restrictions in place which are necessary from a lack of ATC facilities point of view but claim that they are for green issues.