I used the Blauparts kit to change the pads on mine. At 78K miles, my stock pads had only slight grooving, they probably could have gone another 78K with no big issues. That said, if the engine is out, it's reasonably cheap insurance to replace the pads, and you should definitely at least pull the valve covers to inspect the upper pads.

I would guess that oil maintenance is critical to pad longevity. These are metal-on-plastic with splash lubrication, I expect they are not very tolerant of old, dirty oil.