Here's one of my concerns. For instance, I have a sprinkler pump that pulls water from the lake to my underground sprinkler system. There are multiple zone valves that open using the water from the pump. There was a valve failure that caused one zone to not open, so only one smaller zone of sprinklers was open. Because of less flow, the water inside the pump wasn't enough to cool the pump and the impeller melted because of the heat build up. So if your well pump is capable of 20gpm, and is constantly running with only 1 gpm flow, what's to stop the pump from being damaged due to lower flow?
I don't think even the smaller zone was open if you melted the pump. Most likely the pump was pumping zero flow to melt like that. It only takes about 2/10's of a GPM to keep a pump cool. Less than 2/10's of a GPM will melt the impeller. For that reason the CSV cannot close to less than 1 GPM. Your pump will never get hot with a CSV maintaining a minimum of 1 GPM of cool water passing through.