As far as energy use (cost) goes, when choosing between running the pump longer or turning up the SWG percentage to make the necessary FC in my pool I intuitively come to the conclusion that turning up the percentage is cheaper. Is this an accurate assumption? Does doing this have other costs such as "wearing out" the catalyst in the cell quicker?
This is only true if you consider the standby energy to run the SWG. If you take into consideration the cost of running the pump, the lowest energy cost will be the lowest pump RPM that still has everything working well.
Energy use for your pump changes non linearly with RPM. And pump energy will dominate your electric costs. At some point, running at too low RPMs will not give you good enough skimming, may not trip your flow meter on your SWG, and could get into an inefficient RPM range. With my VS pump, I think it starts to lose efficiency below 1000 RPM.
So I'd suggest you figure out how slowly you can run your pump and still get good skimming, etc. Then set your SWG at the percentage that is going to get you the FC you need.
For example, If your SWG makes 2lb/day, and you figure out you want to run your pump at 1200 RPM, and that you want to run it for 12 hours/day [based on the 1200RPM], that means @100%, you would get 1lb per day.
In reality, you don't need to do this calculation because FC use is variable; so you start with an educated guess, and then up it if FC is dropping, and lower it if FC is raising.
So lower your pump RPM, run it longer within reason, and the SWG will not wear out any more quickly.