As others have said, if you want to go properly fast (25-30+ knots) you will need a foil that is designed for those speeds . From what I've read the SAB W1000 ( windfoil racing ) is good for 25kts, the local guys who have cracked 30kts were using SAB 671 wing ( kitefoil racing- small) , the guy who cracked 30 knots at Lake Garda during the racing recently was on a Levitaz R5 - top end current racing kitefoil. The rest of us can forget hitting these speeds on our regular winging foils, they are simply too thick and draggy , even the HA ones. Most people will be doing well to crack 20kts fully powered up. So the issue seems to be the foil , not the hand wing, even though we think the latter is relatively crude it is clearly capable to getting you to 30kts if the rest of the package is low drag and designed for speed.
Yeah totally agree, foil tech is something that is continuously improving, but this is not my specialty, I will probably make custom foils in the near future, but figured I'd start with something I can achieve easily.
And I think I highlighted the massive positive being reduced load, ability to take wing both up and below its range as well as very controllable power. I can ride flatter, more powered sails very easily now.
Anyway, I'll report back when I've changed my full quiver over, I don't think the foreseeable future has time for me to do it myself, but I'll ask if the loft can do it for me.