It's a difficult problem when you basically have numerous aircraft types with varying speed capabilities and limitations shoehorned into ever more congested airspace. It seems that they mostly have gotten it right at LHR but it is obvious to me that there needs to be some standardisation regarding when an aircraft can resume their own speed control. Often there is a conflict between a company's stabilised approach criteria and the speeds that ATC would like to see. As we now have all of our approaches fed via the QAR/FOQA through a computer program to analyse our many faults, we tend to err on the side of the company requirements to avoid the inevitable trip in for tea and biscuits and frequency congestion just makes it more difficult to coordinate our requirements.
Personally, I would like to see a standard of speed at our discretion by 1500 ft. AAL. 4 miles can be a little tight in some types at some weights and the extra 200-300 ft. could make all the difference in the world. I would also agree that the Germans are way out to lunch with some of their speed requests and would benefit the most from some type of well thought out (ICAO perhaps) standard speed control. It seems to me that if ATC knows what to expect and actually gets it, it would make their job easier, regardless of the actual speeds used.