Sounds like you are in CA. For most CA residents, I usually recommend a VS pump and especially someone with a solar system. The RPM can be optimized for maximum heat transfer and minimum energy use. You will easily make up the cost of the pump over its life.

As for your SWG, you really shouldn't need to adjust the salt level much unless, you are losing a lot water via splash out or a leak. Which Hayward SWG unit do you have?