I don't think I ever gave the impression that I think platinum plugs are worth buying or anything. I wholeheartedly agree that non-platinum plugs are better for our purposes.
As for the reason behind a lower voltage spark being more reliable, I wouldn't say that it's more reliable because it is a lower voltage, but because it occurs at a lower volage. If the coil was producing an inconsistant voltage, reducing the level of voltage necessary to cause a spark would improve the likelihood that a spark would occur.
The reliability of platinum plugs also have a lot to do with the material not being destroyed over time. Since the gap stays consistent over a longer period of time, it is less likely to misfire because of improper gap.
Autolite now has titanium coated double-platinum tipped spark plugs which are non-corrosive. Now you don't have to worry about using Heli-Coils.
I should mention that it is possible to get a higher voltage spark with platinum plugs. All you have to do is increase the gap.
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351W 89 Mustang GT Convertible