Great post George. Thank's.
I always have a visiting sensei join my dojo when I grade my students. Just to add a little extra tension and have them experience it as a special event. Also in Denmark it is the rule that all yudansha - and most higher mudansha - grades should be taken at one of the two major annual seminars. We have a small country so it's possible to ensure a certain level of quality in this manner. However the different styles of aikido being taught in the different dojo's show clearly at these events and the panel allows for a broad diversity as long as some basic principles are included for each grade.
It's by no means a perfect system - whatever system is? - but it serves a purpose and we get the best from it that we can.
Now let's all go practice..