The web site says
Developed with Kai Lenny for downwind or open-ocean swell-foiling.
That implies a fairly niche market to me and that would support the $5499 price tag. How many people can get themselves and their SUP foil out into the open ocean to ride swells?
It would be good to see what the result would be in a bay downwinder or a downbreezer (~15 knots). A bit more real world use instead of perfect Hawaiian ocean swells and super athletes riding. If you can get some speed and lift in those conditions then a SUP foil could be a good thing to have.
At the moment a full carbon kite foil and board can be had for around $3000 so Naish had better do some serious thinking about the premium price attached to a SUP and an alloy mast if they want the product to have much of a future.