I have no experience with Vortex.
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I have a Peet Bro pro (big cups) on my tower for well over ten years, probably put up the year they came out with it. I have never had a problem with the concerns about easy breakability that I also read about. Maybe I'm lucky.
The Davis I have on the tower is from a Vantage Pro, NOT a VP2, so that goes back a ways. It, too, works just fine.
Maybe I'm lucky. But as you well know, if one goes to pot, it is a real challenge to swap it out. Most have wires that connect directly to the unit, not easily swapped out. If the cups do give up, or the reed switch or Hall device goes south, it has to be replaced.
When I have gentle breezes, the unit that turns first is the RM Young 5103, but unless you find one inexpensively on eBay and can see if the Arduino can be used as a front end to detect the Sin wave 3 cycles per rotation, the interface may give you some design challenges.
Davis did make a unit to plug either an NRI or Young head into and then that box changed the sin wave into a pulse that the Davis could read, but I don't think they make those any more.
One of the members here did use it and loves it from some of the info in the last (some time ago) post about his set up.
The other thing about the Peet Bro heads is that they sense wind direction ONLY if there is rotation of the cups. I don't think they use a potentiometer the way most other heads do. I think they sense cup rotation, and then time when the magnet goes by where the vane is pointing, so that may be something you want to research.
Just points that I thought of when I read your post. Dale