From a TMA point of view expedite is used more often not because the controller has missed a conflict when issueing the climb or descent but because we have short sector lengths in which to effect our plans and therefore work to far tighter tolerances than Area sectors. I agree that expedite must not be used to provide separation but it is nonetheless a useful tool under some circumstances to provide more of a comfort zone or make a difficult situation easier to solve. It is obvious that a ultra long haul A340 isn't going to be able to expedite, even to the most inexperienced controller, but a large proportion of TMA traffic is not travelling half way around the world and does have a bit extra to give on request. Not only can it solve our problems sometimes but some flexibility from crews can also result in more direct routeings. I appreciate that in a perfect world the crew would be able to set the most economical climb rate and toddle off on their merry way, unfortunately with the way the TMA has evolved this is not possible, if indeed it ever was, and to provide the best service to everybody we need to use these tools. As for traffic drifting down, 500ft per minute is the minimum but if the controller requires a greater rate then he need only ask or include a "Level by" in the clearance.