Anotherthing:
Re above regarding reciprocal headings for separation... if you're worried that a one or two degree anomaly is going to give you convergence on aircraft 6 miles apart head to head, then you are cutting it a bit fine with your separation anyways and I'd suggest that on radar no one is that good at judging distances...
I will fully agree with you on this, however not too sure that the newbies now working with iFacts that have never used any other method would consider this a problem.......