My take is on this is, on a racecar, coil-input is 'fairly' irrelevant (in case of too much voltage) as a coil hardly gets time to fully warmup and maybe overheat in the 5-6 combined minutes the engine runs during a run. The hotter the spark the better.

But in a (daily) driver the coil better not get too hot during prolonged use otherwise it could short internally and fail prematurely.
(Hence I usually check the coils temperature after some running time when I switched resistors.)