I'll try to add my two cents here.
A flush fingerboard doesn't necessarily mean that you need high frets; the bridge (and less so, the nut) raise the strings high enough.
I think the reason behind the flush fingerboards (which sometimes are seperate slices of wood, glued onto the neck, but flush with the soundboard) is in a more traditional, artisanal building technique using a Spanish heel: they are built face-down so fretboard and soundboard are perfectly level, allowing for an easy, rigid and light neck-attachment. Mainland builders (and many after them) preferred the building technique used in non-classical guitars, closing up the soundbox first and then fitting, angling and leveling the neck and fretboard (with flat joints, dovetail joints, screws...), which allows more adjustments.
Anuenue built their Vision 1879 with a flush fingerboard as well, but I can't think of any other contemporary builds, apart from your Ohana... The building technique used is a bit at odds with mass production.