"I’ve noticed that the term ‘spinning mass gyro’ is being used in this discussion, as opposed to ‘vacuum driven gyro’. Does that mean you all are comfortable with an electrically driven AI? That would make sense if the AI contains only contains a simple electric motor which consists of windings and permanent magnets. Those tend to be very tolerant of voltage spikes."
Yup. But.....
"But if the electric AI contains even a single electronic component (voltage regulator, integrated circuit, etc), wouldn’t that make it vulnerable to the same lightning strike that took out my fancy EFIS, charging system, isolating diode, and backup battery?"
Aye, and there's the rub with an all electric airplane. (I own one.)
Life is full of choices which means you have to make a series of hopefully thoughtful decisions.
One could choose a vacuum pump and gyro, but history shows that vacuum pumps fail frequently, much more frequently than airplanes getting struck with lightning. So I voted to dump the vacuum pump and use an electric AI, and then follow the guidelines of current certified all electric aircraft - dual alternators, dual batteries, alternate feed pathways for power, Schottky diode pathways, and I added huge transient suppressors (see Perehelion design).
I could not include the lightning protection put in certified aircraft. So I put big ground lines in to all extremities of the aircraft in an attempt to route any passing lighting bolt around the hot side of the electrical system. Nonetheless, there is no question I could get nailed by lightning taking out all the electrical systems. The defense if obvious: if the Stormscope says there is a thunderbumper in the neighborhood, the decision is to leave the neighborhood. That is probably the most important decision of all.
I do have a vertical card compass front and center. If the lightning leaves that alone, in theory I could use it to keep it pointed in the right direction while I fly the back up steam gages for altitude and airspeed. I have done so flying VFR while my Cheltons were inoperative due to some GADAHRS work.
You pays your money and you takes your choices. You can reduce the risk, but it will never be zero. Thoughtful decisions are very important in the risk reduction process.
Fred