What is interesting to note for all ATC's ...and I speak under correction .....is that there is a clear ratio between priority given (by the auto pilot) to slowing the a/c down VS descending the a/c .....that is of course during autopilot operation and could be influenced accordingly by the crew ....bottom line is .....ATC's should know their "customers" limitations / operating parameters ....and work around them ..... ie. don't expect the impossible ......
I f we all take time to fully understand each others restrictions / operating parameters ...then we WILL work in greater harmony