John,
   To avoid having to install a backup electrical power supply for my
ignition, I kept my left mag (with impulse coupling) and replaced the right
one with an Electroair electronic ignition made by Jeff Rose.  I had a hard
time choosing between that and the unit Klaus Sauvier of Light Speed
Engineering (LSE) sells, but went with Electroair because (1) it has a nice
timing unit that goes into the vacated mag hole versus having to install a
timing sensor on the flywheel for  the LSE unit and (2) it costs less.  From
what I was told, you get about 80 % of the benefits of a dual electronic
system with a single one, so I felt it was worth it.  My eventual goal is to
put GAMI's Prism system on the engine after it's had time to mature.  In the
meantime, I'll be installing GAMI injectors as soon as I have the
opportunity to get the data for them.
   As for MAG backups, Scott Krueger is correct about LASAR having mag
backups if the electronics go on the fritz.  I believe that's what Unison's
EPIC system (their answer to FADEC) will have as well.  On most dual
electronic installations, the backup is normally in the form of either
independent or redundant power supplies.  Each ignition source is
independent of the other, so the odds of both going out at once are pretty
small.  Mine avoids the complexity by keeping one trusty old mag to fall
back on.  So far, the two ignitions are working fine together.
   Skip Slater