I'm guessing brown belt is some where between 2nd-1st kyu.(we use only white belt until yudansha.)
The shidoin I had talked to also had the same opinion of new black belts.
He feels that people are confident in their ability years before they become competent in their abilities.
Lol, I'll have to steal that quote...so true. Um, for my karate I think brown belt started at third kyu. For our aikido; one style has brown belt at 2nd kyu, the other at 3rd kyu. Interestingly both my karate and aikikai groups add stripes to belts while my Yoshinkan offshoot group starts with stripes on their belts and then takes them off as they progress....sorry, that's a little off topic.