Welcome to our forum.
I'm considering a drop-in unit (but would likely go with The Hot Tub Wizard). I have to decide what I think about the aesthetics of it. Thanks for the advice! Much appreciated.
To add on to my question about buying the salt cartridges... Watkins apparently prevents dealers from selling these directly. Instead, dealers sell "water maintenance programs" where they send you a cartridge every four months. Weirdly, the cheapest option is to pick the program that also includes a silver cartridge (goes in the filter) - this saves some $40 over the salt cartridge alone. Two completely separate dealers quoted me the identical price for their program, $116.50/shipment. One dealer I found online (had to request a quote) would send you a year's supply at once for a whopping $9 savings - my dealer doesn't do that. Can you say price fixing? Sure you can!
Something obviously changed - my dealer is now selling the FreshWater salt cartridges openly on their web store without having to buy anything else. The price is better, too, with a three-pack selling for $299.99 (single is $119.99). They also are having a 20% off sale with coupon code WAREHOUSE2023, so I get three for $240.