Thanks a lot for the info!
I've already ordered a grade B gallon, but that's good to know. You've done it for extended periods with grade A before?
I'm actually thinking of going for 14 days because I've got a convenient hole in my Summer schedule. I'll go with the grade B this time, but it WAS really expensive to get it sent, so maybe next year I'll do it with grade A... still expensive in Japan but not as expensive because I can just buy it here instead of having to order it.