Re: Belt System Question.
A couple of times while travelling I've trained at a dojo that does "casual summers"--in the summer, everyone wears white belt and gi, no hakama.
I remember doing a whole morning of jiyu-waza with six or seven of them, and being told at the end, "That was well done, especially since you're four ranks lower than the next lowest person here." I'd suspected as much by about five minutes in.... If they had all been in black belts and hakama, would I still have been there? Maybe. I'd have been intimidated right up front instead of five minutes in, when it was too late to back out.... It was a good, if scary, experience.
We have white belts and no hakama till shodan, black belt and hakama thereafter, except that if you are teaching you wear the hakama regardless. This works well as it's a clear visual marker for the teacher. We've found this particularly important in kids' classes; a teacher in gi and white belt does not have as easy a time controlling the class as the same teacher in hakama.
The one place we use colors is for kids, and I find that really helpful for a number of reasons. There is a natural tendency to think big kid equals experienced, small kid equals inexperienced. But it isn't true, and the belts are a strong visual reminder for everyone concerned. And they are just more motivated by belt colors than by number rankings. (The blue-belt kid is currently annoyed that both 6th kyu and 5th kyu are blue, so he has a long way to go to purple.)
When I was training at an unfamiliar dojo with a ton of young students in open classes, I think those colored belts kept me from making a lot of both social and aikido errors, and possibly getting pounded into the mat by smallish brown-belts.... Somehow it is easier to look at an unfamiliar
adult and assess their ability level than to realize in your gut that the eight-year-old holding out his hand is fully capable of taking you apart.