Hi Roger,
Some of the more expensive units have reverse polarity protection & current limiting or shutdown to prevent overheating if the ignition switch is left on with the engine not running.
Depending on the resistance of the coil that is being used, the Pertronix can be left on quite a while without overheating, but usually not for hours.
In my opinion, the Pertronix is a definite improvement over the points & at fairly low cost. It just won't withstand being installed or wired wrong. If a person pays close attention to my above suggestions the Pertronix will work very well & last for a long time. Just no careless installations tolerated. I have had four of them that lasted for years with no trouble, no points setting, checking, replacing, timing checks, etc. The "Hall Effect" timing sensor on the Pert. is less affected by dirt than the optical sensor types, & less sensitive to parts locations than the magnetic types.
D