I'll try to answer 2 posts in one.
As a qualified tradesman, I had to swear an oath of lifetime hate for DIY products.

They suck the consumer's money; often overpriced with dubious knowledge behind a warranty. Look at concrete - how much do you pay for a cubic yard from a truck, opposed to buying 120 × dry-mix bags at Home Depot?
The Pertronix is squarely aimed at the DIY market. Priced right, simple to install, wide range of applications. Some problems:
We have noted one model (not sure if I or II) did not fit some breaker plates. That was after the purchaser bought the
exact number part recommended by maker's literature.
The insulating tape is wound the wrong way for our six cylinder distributors. If the end comes loose, it reels off. It is a simple fix on the production line and I don't believe the factory is on top of it yet.
Pertronix Ignitor I has a noted problem of risking burnout if ignition left on, motor not running. It's one of the reasons the II version is made.
The Pertronix Ignitor II has noted occurrences (on this board) of poorer performance than points, when installed in accordance with factory directions. WSA III suggested that it could fail just in the most dangerous time possible, like turning across oncoming traffic.
Both the ignitor I and II rely on the mechanical aspects of an old distributor. You are only as strong as the weakest link. The vacuum only Loadomatic distributor is difficult to tune on a non-standard motor, or even a worn standard motor.
A Pertronix will not fix the inherent poor performance of the factory part in these cases.
The dual advance distributors wear and deteriorate with age. In addition, many are rebuilt with the wrong internals - again, documented this site. So - what will a Pertronix do to improve the basic flaws in this situation? Not a lot.
The Duraspark is a better distributor setup because it inherently has a higher output than the standard points systems. It is also most suitable of the US Ford six distributors for adding a control box such as the MSD 6A or Crane Hi-6.
I often see this argument about "What if the car breaks down on the side of the road?". Well, my retort is there are plenty of things that can go wrong; why not prepare for them all - or better still, tow a trailer with a spare car on it so you have
every part available. Seriously,
the Duraspark system is well-proven and more fault-free than points. Certainly less problematic than Pertronix.
A final roundout. In my opinion, the '85-87 Aussie distributor is better than the DSII but it will not fit later US motors without modding. That takes it well out of price contention. The closest American setup is Duraspark II, GENUINE GM module, TFI coil. It requires a little work to install but the reports on its function are extremely positive.
Regards, Adam.