Electronic engine controls: good or bad?

Good choice, but what does low voltage have to see with your Hynautics controls?
They need no current at all, AFAIK.
Or did I miss a separate issue?

Was also the stop solenoid jammed?
That would be a weird concidence, 'cause usually they have nothing to see with the control levers.

For some reason I previously missed your reply.
I'm no SF expert at all, is that a behaviour you would expect from any of them?
A sudden total loss of power on one side (at any speed) is one of several tests that any yard should do on their boats, and the reaction should remain smooth enough to avoid the risk of throwing someone overboard.
I'm even aware of some cruisers that can stay on the plane with just one engine.
But even those (the majority, in fairness) who don't, normally react to the situation you describe by slowing down and turning on the dead engine side, but nowhere near as hard as by steering hard over.
Maybe SFs are designed with props more far apart for better maneuverability? Just guessing...

Mmm... Did you actually try that with any other boats?
As I said, it should be part of routine tests for any new boat.
And a total power cut on one side should never create any dangerous condition, even at WOT.
That's with no rudder action BTW, i.e.keeping them centered.
If anything, the a/p should have immediately reacted contrasting the turn.

PS: I'm well aware that the behaviour you described is unavoidable in an offshore boat running at very high speed.
That can indeed be very dangerous, potentially leading to a hook and spin, if not even a capsize.
But at 25kts? That rather sounds like poor hull design...

Spongy hynautic is likely calling for a new set of seals at one or more location in the chain of stations and slaves. But spongy hynautic is still reliable. I'd always lean to mechanical over hydraulic, hydraulic over electronic...if the vessel allows you the option.

Yeah, I can see how that experience would tighten your shorts. Thankfully, as you said, you were in the open. My luck would find me between two jetties in a nasty inlet.

I was sitting at dinner at the dock at Houston's in Pompano Beach when an electronic failed and ripped the place up pretty good...you have what you have with electronic engines, but that thought is forever in your head when you've seen it happen. Me? Lightening strike nearby, not direct, took everything including sensors and injectors etc on the mains. Thankfully I was neither aboard nor underway. Big expensive mess, and then along came Pantropic to make it even more pleasurable.