I owned a Questus and it was a beautiful piece of gear. Unfortunately, and IMHO, they are just NOT worth the money. I barely noticed any performance difference from the pole mount I converted from.
The bottom line is a dome on the spar will perform better. The self leveling units make all kinds of interesting claims, drawings and graphs that just don't seem to pan out in the real world. In my many,many years as a commercial fisherman and sailor cruising the North East coast, specifically Maine and the Canadian Maritimes, I have learned one thing.. There is no substitute for height. Trust me in ten foot seas pole mount domes return squat and I can say this because I unfortunately, currently have one that came with my boat..
I researched every one of them when buying mine and by a large margin the Questus was the finest made unit at that time. The owner of Questus owned a medical device company and took that level of construction to the Questus. He actually hand delivered it to me and the service was exceptional. I just wish I could honestly tell you it made a difference but it just did not..
Theory is nice but real world performance is what matters..
Nice concept but a waste of money IMHO. Tell your buddy if he wants a tool he can use, when he really needs it, to put it on the spar. My pole mounts have let me down many times when I really needed them like in 12 foot rollers and pea soup.. Intermittent target acquisition sucks when in the troughs.... Then again I sail in fog a lot more than most so my performance standards are probably a lot more critical..
Our Questus Boat:
On the next boat I went right back to a mast mount:
And now I'm back to a pole