so unless your giving a cardinal point (for example if you only have four options) the instances of RSI amongst ATCO's is going to increase.
I can't see that ever working in a busy radar environment. I for one use plenty more headings than 4..
I'd spend half my shift typing and how would that work when it comes to a handover time. I'm guessing if EFPS was used in a radar enviroment (non AC) then the majority of ac will have to follow SIDS/STARS to reduce the amount of manoeuvring involved.
Just my tuppence worth