Its a difficult one, or maybe very simple in fact.
The Quark is apparently the only digital gyro that works just perfect
My friend had a REVL too, but it can not hold the horizon (and now they are apparently out of business)
But we all know now, that the Quark isnt fully watertight.
The same as watertight pocket cams, you will sooner or later get water inside, as just a teeny weeny sand grain in the sealing, and the camera is toast - thats how it is, we all know that.
I've had mine (Quark) in the water a couple of times, and rinsed sand many times under the tap, and it still works.
But I KNOW, if I get it down for a longer period, it is toast.
Thats just the way it is, quite inexpensive (quarter the price of a good kitecam) so not that bad really.
The worst thing is the long waiting time
So I see it like this, we know it isnt fully watertight, and take a chance every time out - but it is worth it when looking at the video and pictures, nothing comes close in terms of stabilization
I had a kite with a repaired front tube - it suddenly blew up in the air, and my (watertight Sony) kitecam went down 1 m under the water while I was swimming ahore.
It did not survive, almost expexted, 50 50 chance.
The memory card worked, so could see the explosion afterwards, quite funny.
These cameras are a "wear" thing in my experience, after many years with action and kitecams, its just the way it is.