FlightPath,
I agree the FAA mandate the use of 'Heavy', and that it has it's uses from an awareness point of view. Other states don't however, and so we're back at the same old point of there being ICAO regs, but them multitudes of state differences. These can be very difficicult to 'stay on top of' for users who are in different countries every day flying :-(
Even with the above phraseolology being used, aircraft positioning visually behind each other (variable gaps!) certainly do not produce the best runway effeiciency, or predicatbility, in my opinion.
Rgds
30W