In a recent danish 30 km race around the island Venø with 45 windsurfers and 3 kiters, the two hydrofoil kiters Bjørn Rune and Steffen Øvind covered the distance in 51 and 54 minutes respectively. The fastest windsurfer arrived at 1 hour 6 minutes.
(btw. the surname Øvind literally means "Island Wind" in danish)
I do not have the wind speed for the day, but reportedly the windsurfers struggled to get planing.
A hydrofoil is certainly the most efficient way to travel across the water. In some ideal conditions a hydrofoil can point higher and go faster than a race board. But a modern race board can also act like a "foil" where the fins are acting like hydro foils and the hull is barely touching the water (this is why we edge race boards with the leeward side of the board).
Race boards are easier to ride and seem to handle a variety of conditions better. They certainly go downwind better. Nobody is competitive in world class races with a hydrofoil ..yet. Remember that whenever a hydrofoil board drops down to water level it is very slow. Also remember that a hydrofoil design is optimum only for certain conditions of speed and direction, while a race board can handle a wider variety of conditions well. In any course race you encounter crowded tight conditions sometimes and the ability to maneuver quickly is crucial. Perhaps better foil shapes and more skilled riders will improve the hydrofoil standings in races someday.
I've only ever carried one of these out through the shore break into deep water for someone to have a go on, but it is cumbersome when in the water, so since these are light wind weapons, I'm interested to hear what the riders do when the wind drops to where the kite wont relaunch.
Self rescue on a raceboard should be easy - not so much with a foil?