If faucets should be stainless steel, not brass to avoid off flavors,wouldn't the brass thermowell in the fastfermenter create the same off flavors?
Brass has been used for a long time in brewing equipment. If you want to you can "pickle" it by soaking it in a 50/50 solution of vinegar and hydrogen peroxide to remove anything left on by the manufacturing process. After use it will tarnish and have a layer of oxidation on it so your beer won't technically be in contact with it. Just clean it but don't scrub it off. I would not worry about off flavors.
Thanks HD I appreciate your time
A review of a brew? Sneezles61