The Aires I had was old, I had it in early 80's! The monitor was a lot better. My aires was likely well worn when I got it , so there is that consideration also. One problem with the early ones is the components tended to get corrosion on the aluminum joints and very difficult to disassemble. I abandoned wind steering devices after several years and just used good autopilots. But I never made the long trip across the Pacific etc. I could see the vane being nice on that. It seems most the time the trade wind is variable and you are always tweeking the vane constantly.

I'd value your input: how did Monitor & Aries compare? particularly when used on the same boat! Was your Aries the "old" model with the paddle-shaft in rollerbearings (not bushes as nowadays)?