I ran a Wells replacement 4-pin ECU and an Accel Super Stock Street coil with no ballast for 6k miles and never had an issue. I currently have the FBO ECU and the FBO coil without a ballast (when I re-wired the car there isn't even a place to connect it), and 2k miles later, still perfect.

The voltage going to the ECU is always full battery voltage on a 4-pin car. Cars with the dual ballast have one side for the 5-pin ECU. I doubt the switching of the coil at 12V vs 5 by the ECU will have any effect on the life of the ECU, as it's not a high current draw there (check out the small wires).

Plenty of coils out there that can take 12V. As people have said, you don't use a ballast with pertronix, or with MSD, or with an HEI conversion.