I didn't try crashing my kite.
But I shook the kite plenty while setting up. The mount seems quite solid. I'm making another PVC ring with a narrower gap for better security.
The wrist strap might work. I used the vented helmet strap a few times on my 12 m, but it wasn't snug on my 6 m kite. Also, using the helmet strap required using additional mounting hardware and careful adjustment of the camera position to get the kiter in the center of the field of view. I had several sessions where I worked hard to get video, but the camera was pointing the wrong way. With the PVC mount, I just put it around the strut, pump up and I'm good to go. I think it would be harder to fiddle with the wrist strap, wrapping it around the strut near the leading edge and then getting the angle right, especially in cold weather. I always found it a PITA attaching the vented helmet mount to the strut.
I sanded down the PVC so that it wouldn't grind against the kite too badly. Of course I know that with salt crystals or sand there's always the chance for abrasion, but I will watch it and see how it holds up.