I remembered that some time back I asked this very same question on the Airheads list.
"what is the benefit of the later electronic ignition coils which must pull something like 8 amps when the recommended spark plug gap remained the same at .024" - .028" Unless variable dwell is employed by the black box the extra current draw represents a fair amount of additional load on the electrical system so there must have been a good reason. In the real world do the electronic ignition bikes perform any better."
This was the response from Snowbum.
"The later coils, and the electronic ignition coils, do have a much lower primary resistance and do draw considerably more current. One could get deep into this and talk about average current drain, and then bring up the subject of the differences in DWELL, which greatly affect the average current drain, versus rpm, and so on. I don't want to get into this, not really necessary here. The pertinent fact is that the later coils, especially the electronic ignition coils, produce a lot higher ENERGY spark. That is measured in Joules, for the nerdy here. Also for the nerdy, the ignition module is designed for a relatively fast turn-off, which creates a somewhat faster rising waveform. These things are needed due to the LEANER mixtures used on the later bikes, due to smog considerations. Leaner mixtures are more difficult to 'fire'".
The conclusion I drew was that the electronic ignition did produce a higher energy spark but this may only be of benefit when firing weak mixtures.
The potential down side of electronic ignition pulling twice as much current was not clearly resolved. If the electronic ignition module under the tank does have variable dwell control then the overall current draw will not be double but it will still be higher than with points ignition coils.
