Well, KFBox is a specific box for kitefoils, low build height, strong, and fast to mount, it comes in standard KFBox and DKFBox (Deep) for racefoils.
Tuttle box is the worst standard EVER, for kitefoils, it comes from windsurf with the triangular stern of windsurf/windfoil boards.
So was adopted for kiteracefoils because you could get these box'es everywhere.
What a shame, the DKFBox is perfect, conical and with a straight top.
History is, that besides Ketos, Alpinefoil also use KFBox, and F-One used KFBox on all their earlier foils.
Till now where the wingfoil and platemount is so used, that they changed to this also.
Gong and F-One and Zeeko and most or all other brands has adapters for KFBox and Tuttle, so easy to get.
Major problem is, some use two screws, others use one - so they are not always compatible, bugger