I don't use the Kayfun but I bought a Provari Radius they day it was availabe for Preorder. Using it daily since I got it and it's the best piece of equipment I have. The parts and materials are very high quality and the performance is excellent (accurate, good features, never fails). I started to sell some of my other gear since I don't use it anymore.
And yes, there are some Provari users that sound like they make a religion out of it. But it is more that they just enjoy their gear and share their satisfaction with other Provari users. That can make a visit to a Provari threat a somewhat strange experience as you feel like you stepped into a family gathering or some secret club meeting. But it's actually a very warm and friendly community (as long as you don't start to troll intentionally) that made some nice gestures, like donating money and buying a new Radius for another member that could not afford it (they brought the money together within a couple of hours).
Another part of it is that Provari is made in the U.S. so it is also a matter of pride to own a "made in USA" mod (for the members in the US)