I am a Uk pilot who has flown out of the major southern airports for over 20 years and have to say I am surprised at some of the comments. If a controller asks for 200kts, 180 kts, then 160 kts to 4dme, then I do it. It is something the controller has ask me to do so no question, I do it. If I think there is some reason why I need to maintain a different speed, then I mention it to him/her just so we both know the situation. One obvious example is knowing track miles to run, and my altitude, I can calculate if I am going to be high or not. If a speed change adds to my situation from a negative point of view, then I will politely mention to atc that I either need more track miles, or a faster speed for a little while. This is just one example.
126.82 - I assume 3-4 mile seperation in non low vis conditions is the minimum seperation? so any speed violations by pilots will cause a delaying in the approach. Also in these days of upgraded TCAS, just how helpful is a constant a/c speed readout to you? So do you sometimes feel you want to issue some a/c with a 'ticket' who obviously ignore you?