I own and ride both a raceboard (North LTD 2013) and a hydrofoil board (Carafino). Certainly my raceboard is faster. But there are faster hydrofoils than mine out there now.
When riding a raceboard under ideal conditions, the board barely touches the water and the fins act like foils. And raceboard fins have gone through intensive development in the last few years to optimize their performance at high speeds.
A very fast hydrofoil board should beat anything going upwind in a straight line under ideal conditions. But I have tried to use my hydrofoil racing and it is a problem when rounding mark in crowded conditions. It is also difficult going downwind (actually it is a bit difficult all the time
). And I am uncertain about the range of a hydrofoil board. One that works for light wind may not be capable of high speed.
Don't be too quick to presume one board is far superior to the other around a race course.