javelin,
The LIFFY restriction is about getting you into a particular sector in order to ensure you then make a subsequent Standing Agreement.This is the "network " effect taking place. I suspect if you were allowed to cross LIFFY on the normal profile the workload for S7 against Dublin outbounds and other Shannon outbounds would be so high as to reduce the sector capacity. You would then be the 1st to moan when you get a regulation and subsequent delay. If that were more than say, 20 minutes your company would then refile and I bet the additional fuel burn would be considerably more than 500kg!
The Operators have stated that throughput on the sectors is to be maximised and if that leads to inefficient profiles then so be it. It really is swings and roundabouts on this one. We will leave you high if we can and much of that area is dependent on the Oceanic traffic loading.
If you want to PM me and we'll talk more off line and I'm always available for a BGI fam flight to see the effects on your fuel burn.
On the subject of the LAM3A it is high time we were allowed to just instruct you to descend "on the profile" as they have been doing at LAX for at least 15 years. RT loading is reduced and there is no ambiguity as to what is required from the crews.