I'm in the Arai SB club, well i used to be.
Had the SB 600, open book headstock, ( as opposed to the Batwing ) and it was a set neck, single pickup. Lovely to play if you like slim necks ( and boy are they slim )
and 16.5mm string spacing, which i adored. The only trouble with it, from a personal taste POV, was the lack of mids. I think the single pup was in the wrong position, but thats just my opinion. I would certainly like to own the SB 900, which did have the twin pups.