Re: History of Black Belt?
The Shodokan curriculum is standard inside and outside of Japan. All things being equal there is a difference between those that spend time at Honbu and those that don't. As for uchideshi they are taken from a pool of talented students that have usually had extra attention paid for some time. The end result is always something quite special.
Statements along the line of a Japanese Shodan is worth only a 3rd or 4th Kyu is outside of my experience and essentially meaningless. How long have you been doing Aikido and who with, followed very quickly by let's see what you got. That's what's important.