I don't think you can get away with not having all 600 days unless your teacher is a Shihan. If you go to test at a Seminar where the Shihan has no personal relationship with you I don't think you can get away with shorting out on the days.
A lot of people were excited at first when they realized that shodan requirements were cut by 100 hours. However, they got upset when they realized that 1st kyu was now required to attend 2 seminars a year in order to test. I mean I'm in my early 20's, no kids with a double income, so I can hit seminars as much as I want. But a lot of people have kids, wives that don't do aikido, etc So if your Sensei doesn't host at least 2 major seminars a year they might not be able to go out of town for them to meet their requirements. (Heck even if Sensei has seminars and invites other schools, people still might not show up all the time...having young kids and working retail can be hard for that stuff.)
At AOC the 1st kyu test rivals the shodan test