Gee thanks TW! The best thing for a submersible is to start quickly. The motor has to get up to at least 50% speed in one second to prevent the thrust bearing from running while dry. The motor needs to be at 50% speed before the hydroplane effect develops a film of water between the plates on the thrust bearing. Slow starting the first 50% of speed is one of the worst things you can do to a submersible motor.
Stating the pump against an almost closed valve, as with a CSV, is the best way to start a pump. The CSV gives a mechanical soft start and soft stop. Starting a pump against an almost closed valve makes the motor think there is no load. Starting the motor with no load does not cause the 3 to 6 times spike in amps on start up as when stating the pump at maximum flow, as it would without a CSV.