The Petronix conversion is WELL worth the investment. I, too, was having problems with my points and my car was stahling on occassion. Then, after my engine rebuild, we couldn't get the car started for over an hour. Why? The points were closed. We yanked them right then and installed the Petronix parts. (We wanted to wait until we got the car going before doing the conversion to narrow down any problems we might have in getting it to turn over).
While many will say that no one can tell that you have electronic ignition, that's not entirely true. There is one extra wire running from the system under the distributor cap to the coil. If someone is quick, they'll pick that out immediately.
However, if your Mustang is a daily driver like mine, by all means save yourself LOTS of grief and do the conversion. You'll be happy you did.
Doug
'66 Coupe w/ 289 4bbl.
Power steering, brakes, and A/C
Signal Flare Red w/ white interior, bench seat, deluxe seatbelt option, styled steel wheels, and
an extra seatbelt in the back for my three kids