Either 8hr use or less, overtime the inverter will payback the cost. Compare non inverter. The cost of the pipe and the aircon won't different alot.

I m using 1.5hp inverter with about 20ft of pipe. The cost + install is RM2200. With everyday usage of 8hr, monthly save is about rm40-45. 1yrs save me rm540. Service 1x peryear is rm100. It take me 2yrs to get back my money save compare non inverter even include service. The amount save is I compare with my last time non inverter unit.

So either 2hr or 8hr use, I still will go for inverter. Payback either long or short. Just my experience.

R410 and R22 gas is depend how enviroment friendly you are. If you care and want to contribute a bit to the enviroment, than change it. It doesn't cost you much. You don't need to top up every year.