>Interesting side note that we generally consider 6V systems inferior to 12V.
>Is this just because 6V systems are all very old, and they are having to fight old, oxidized connections, and having to push twice the current through (v. a 12V system) to get the job done?
Can't speak for all old vehicles but certainly Lucas supplied British bike makers with many lower-Amps/Watts components for 6V systems. When Zeners first became available for charge control, not only could wiring be simpler, operation was too, they were 12V; certainly Lucas supplied more-powerful components rather than cutting the Amps consumed.
>I can't think of any reason why a 6V system WITH CLEAN PROPER CONNECTIONS should be "worse" than a 12V system.
In theory; you'll be aware of "Semper Gumby" and his bikes on BritBike.
However, in practice, the average vehicle owner is a lazy git - vehicle makers and repairers will tell you it's hard enough getting owners to maintain the bits that can be seen - electricity can't be seen so why would they want to pay to maintain it when it doesn't go wrong? 6V is simply a lower potential difference than 12V, so more likely to stop working sooner.
>Matter of fact, wouldn't that imply that a military-style 24V or 28V system would be even better for a bike?
Yes, but it requires better insulation. Rightly or wrongly, even if not governed by the first commercially-available Zener diodes, the automotive industry chose 12V.