Lurking but wanted to provide some feedback... Local beach is Belmont Shore, CA and this year we have around 12 kite foilers out of the regular 50 or so twin tip and surf board riders. 2 - 4 regular wind surfers at this beach although the common beach for the wind surfers is outer beach at San Pedro, CA.
Normal Windsurfer transition to kiting is to twin tip first so that kite skills are perfected before moving on to surfboards and hydrofoils.... Learning how to fly a kite takes time irrespective of previous water experience. Learning how to kite foil can be brutal and can take time. Took me more than 16 hours before I was up foiling.
More kite boarders are making the transition to kite foiling and there are many brands to choose from - Alpinefoil, Horue, Liquid Force, MHL, Slingshot, Mosus, Spotz, Taaroa and so on. Low aspect ratio wings as shown in the Maui video are slow easy to learn on. Many of the modern foils allow interchangeable wings so you can swap between a large light wind wing to a smaller race wing... I personally have three front wings to choose from.
'Lightest wind for me is 6kts with an 18M foil kite and I have a quiver of 9/11/15/18M foil kites together with 7/9/12M Leading Edge Inflatable (LEI) Kites. I prefer my foil kites to LEI kites but will use LEI's on gusty/high wind days.
Boat speed for foiling is around 12mph and depending on wind, normal cruising speed is around 20mph with a top speed I can hold with my performance wing of around 26mph but the racing guys and gals are 30mph+
Kelp - Most foil struts/masts have pretty sharp leading edges and will slice though single strands of kelp and weed but anything larger will knock you off.
Kite foiling offers the opportunity to use smaller kites and kite in lighter conditions. You can go faster than a twin tip or surf board and point as high as a yacht to the wind on the water. Numerous styles of kite foiling including race, freestyle, wave etc. Big swells are very manageable on a kite foil - Just need to move up and down and carve through the troughs.
The other innovation that has occured in in the last three years is the development of high aspect ratio foil kites which complement kiteboard foiling very well with upwind performance characteristics that match foil boards.- F1, Elf, Flysurfer, and Ozone are some of the foil kite brands.. So foil kites and foil boards are very popular and a requirement on the race course.
The video shown above with the wind surfers racing a kite is dated only that a modern kite foil racer now uses large foil kites (15M/18M) together with a Foil Board and the large foil kite provides a huge advantage downwind... Attached is a video from the Mexico event from a few weeks back...
Horue has done much to promote Kite Foiling and Wind Foiling but I have yet to see a Horue foil... Just not that popular here in the USA...
A nice foiling race which also shows some of the foiling innovation in other boat classes...
Finally... Me and two buddies foiling in about 10-12kts of wind... All of us are on foil kites together with foil boards... You can hear the awesome sound of the wind through their lines as I pass them.