As far as I am concerned as long as you meet the 13,000ft height requirement by the appropriate STAR point, descent at whatever rate you like. If I need you to get down faster for whatever reason I will tell you. If when told a rate and you don't comply (so as to save fuel) you will burn more fuel going on a scenic tour of the Gulf, just as happens when you try and cheat on the speed restrictions.
Bottom line guys is we give speeds so we can either not vector you or at least minimise the vectors. If you don't comply with the speed that doesn't change the spacing we have to give Dubai, so we will find an alternative, which may be best case scenario a vector, worst scenario, we will stop your descent and run everyone else through who are doing what they are told while you hold. That will be done and has been done. If you can't fly the speed as instructed tell us sooner rather than later so we can make alternative plans.