I've taken lessons with a few instructors in Oahu for kitesurfing so I can say with full confidence that this is by far the best one on the island. I'm dead serious - just go with Maui.
Here are a few reasons why:
1. He has a boat. That means instead of losing your board in the water and spending precious time having to body drag and locate your board, he actually just brings it back to you. For me, it meant I was able to have "many shots on goal", giving me a lot of opportunity to try to get up on the board during the water start. Not to mention, you can get immediate feedback from him. Compare that to other instructors where you literally aren't getting any feedback (very few instructors have two-way radio headsets in Oahu) until you get back to the beach.
2. He takes you to a location where it's just you and the calm flat water. Most kitesurfing schools will have you at Kailua beach. However, it's a crowded beach with a small launch area and when the wind is good, the waves are choppy and there's a bunch of other kitersurfers, windsurfer out there. For a beginner like myself, that's stressful.
3. He's calm and patient. This is more of a personal learning style but there's already so much to think about when you are on the water (flying the kite, grabbing the board, getting your feet in situated correctly, starting to do the power stroke all while trying to incorporate the feedback you just got from a failed attempt) so it was made much easier for me when you didn't have someone who would just tense you up from his demeanor.