Did you ever find a good case? I broke my Fre case, and then destroyed my leather case when my phone slipped out of my thigh pocket on my motorcycle. Amazingly the phone survived, so I'm thinking about another waterproof case.
I've also been looking at a Garmin Vivoactive watch for tracking kite sessions, but I haven't been able to confirm that it works well for that. I've heard the 920xt is good, but it's huge and $500. The apple watch is a non starter due to crummy waterproofing and no gps.
It occurs to me that a phone is good insurance on the water, if it works, but I've broken several waterproof cases now, luckily not on the water yet.