Sounds like you simply had a bad Pertronix unit, there's nothing inherently wrong with the design that would cause your issue. It's a Hall effect semiconductor sensor, and it sounds like you just had bad luck with two of them. I can easily see how your results would sour you on the product or concept. Mine has been in for five years. Once installed, it allowed us to determine that I too, had an intermittent misfire at about 2500rpm--but experts determined that to be a lean midrange mixture cured by internal adjustment of the fuel pump. Once that was done, all was well.
My experience with the Crane was great. However unbeknownst to me it was installed incorrectly. The mechanic had chosen the wrong size (too large) a shutter wheel; this wheel interfered with the pivot pin that is swaged into the breaker plate inside the distributor. As this was no longer needed, he yanked the %$#@ thing out! This rendered the distributor impossible to convert back to a points model, as without the pivot pin you cannot install points! I did not know this, as the unit ran fine for five years. Then, for no reason I can think of, the wires required by the Crane that run inside the distributor decided to leave their comfy positioning, rise up to the shutter wheel, and when they contact the shutter wheel, it stops turning and the car dies. This was a maddening problem to have as it was intermittent and the only way I discovered this was some scuffing on the insulation. That's when I removed it, sold the unit, and bought a Pertronix.
Thankfully I had a good friend here with a prototype shop. He machined a new pivot pin and swaged it on the breaker plate, and the new assembly was sent out for rebuilding. So the damage done by the first mechanic was undone. In my distributor rebuilding there were a few worn parts that were replaced...
The ultimate is the 123 that a lot of people swear by. I know this is a good unit, but I'm a bit put off by a company with no address (that they'll admit to) and one that states they don't want to answer emails...