You really don't need to start changing standards, 160 to 4 is common the world over. Speed limits terminating at 4 is in tablets of stone, and so is the recognition that there will be some erosion of separation inside 4 miles (not so for 5). Any time there is a sensible HWC 160 is achievable, the only time it becomes a problem is when there is a TWC or in some cases still air, or the crew haven't used power against drag in the run up to 4 miles when necessary.
It seems to me that crews should be encouraged to tell director what speed they can maintain to 4 and you can adjust the spacing accordingly. If pilots are liars they should be filed on individually. If a companies SOP's make them all liars then the SOP needs changed.
This shouldn't be a problem, pilots are capable of getting it right but some are just choosing not to. The guys in the light 319's etc aren't shy when they offer a good rate on departure but they keep quiet when they know they need to slow early, that's cr#p. 747 slowing early, if you spot it early tell him to speed up if they cant ,round you go they will get the message. I guess then we can have a fuel emergency thread again.
Leave the bulk of us alone, sort out the people taking life too easy.
IN