Panamax also rates their spike protection circuitry as having something close to infinite life for all pratical purposes, barring direct lightning hits

I never could find the stats explained ? how Panamax is diffrent just comments to the effect that theirs was a more 'hybrid' (for lack of better word) implementation of MOV and feasiblly might be more coverage than other choices. Been delighted with mine. It seems to handle the on/off wackiness of my neighberhood power interuptions very well.
I still hope to add more layers of defense in future, you know best laid plans of mice and men.

Really after doing the research I have done its crazy I have not added minimilist main panel protection. Its so cheap compared to even the loss a one microwave!