[jim-frank]

Kit- it sounded to me like your system was using a capacitor to peak a pulse, not to create a sustained AC arc over 90 degrees of crankshaft rotation.

It isn't necessary to send a huge amount of energy or power through the sparkplug; as you've mentioned, that causes extreme wear. The idea of using a flyback transformer (at least in my idea) is to create a sustained spark to make sure that the fuel mixture has been exposed to conditions that can burn any burnable mixture that is in the cylinder.

As far as H-bridge vs fewer components, it's a wash in my opinion. The minimum component solution isn't always the most reliable one.

RF interference is very relevant to me, as I'm both a ham radio operator and a broadcast engineer. Your example of arc welders not interfering with the wireless connection in a shop is valid, but wireless networks are pretty robust with respect to random RF, particularly as arc welders deposit most of their RF energy quite a bit lower in the spectrum.

Really, though, RFI isn't an issue unless someone was to attempt to commercialize the technology.