Most race kites are available in 21m size now. Does it give you noticeably better low end than an 18m race kite? Or does it just allow you to go faster on shorter lines in the same wind?
Asking specifically for riding race hydrofoils. From what I've seen, the best absolute low end is on a big surf wing with a smaller foil kite on super long lines, but that's not as appealing to me. I really love going fast in light wind when the water is mirror flat.
It's interesting how things have progressed. When I went to my first race 4 or 5 years ago, I remember a top racer saying we will never need a kite bigger than 13m for hydrofoils. Then foil kites came out and everyone got 15m kites. Now most racers have 18m, and the 21m is available. Most are using <15m lines for all kite sizes.