Hi,
I installed the Pertronix about 5,000 miles ago. I have an original dizzy with a worn shaft and a very little play. The Pertronix really improved throttle response. So far, I really like it. Although, would like it if they produced an Ignitor II or Ignitor III for our cars.
If mine does eventually fail, it will probably be b/c for the first 3,000 miles I had the low ohm coil (1.5 ohm PN 40011) installed rather than the correct one (3.0 ohm coil PN 40511). My understanding is that the low ohm coil sends more (too much) juice to the ignition (I may be wrong about that).
Bill, regarding your voltage drop, I had a similar issue. First check voltage across the battery terminals. Then check it at the coil. You should see no more than a 0.5 volt drop. Originally I had 12.45v across the battery and 7.10v at the coil. Traced it back to horribly corroded connectors on my ammeter. Replaced those, applied dielectric grease. Result, 12.55v at battery and 12.45v at coil. Now she fires up instantly upon turning the ignition key.
Bob