Thanks for sharing this info, Dave. This is consistent with what I had understood as well and is greatly appreciated.
Other than the maintenance free aspect of the wet-rotor, would it “foolish” to go with the old model for any reason? It had served us beautifully for 15 years and we do annual preventative maintenance in any case. If we are going to change it out again - there is a certain peace of mind with going with what we know worked.
Not sure if this is broadly posted or not - if it is, many thanks to everyone else for there valuable input here.
Sorry for the delay in getting back to you. There is only one reason for going back to the original type of circ. That is for fitment issues.
Since your flanges have been updated and a wet rotor circ is designed to be maintenance free and last longer than three piece circs and also use less electricity. I would go after that.
As for all of the other comments about piping and components and all, they are true and can help the system, but remember; it worked the way it was for many, many years.