No regrets on our whole house Briggs and Stratton unit. When we were in the market, it was between Kohler, Generac, and Briggs. Went with Briggs because it was the only one at the time that had a 400 amp transfer switch that was designed for 2x200 amp sub panels. Don't think you could go...
I have the same exact issue and am glad you posted the thread. Pump itself appears to be 100% fine, clean, impeller intact. It'll run for about a minute and then start to reset/power cycle every 3 seconds after that. Guessing it's the controller.
Since ph is exponential, you'll be surprised how huge of a difference you'll see by going just a bit lower. 6.5 to 6.4 is a big difference. The lowest we ever ran was about 6.25, and that burned up about 40 lbs of media every 4 months.
Incase you don't find what you need-- I've got a huge green slimer colony I need to trim (like 18"). As well as tons of other stags, Bali slimer, and many others. And asd rainbow as well. If you're willing to drive out here, will make it worthwhile :)