Having owned pretty much nothing but EFI vehicles, I can honestly say I've never had an EFI failure in hundreds of thousands of miles. I've had alternators go out, or an occasional coil-on-plug failure, but never an issue from the EFI-system itself.
The electronic distributor on my boat has saved a good bit of annual maintenance by not having to check points, etc. and has made all operations silky smooth just like a fresh set of points that last forever.
There's little reason that several of the modern tech items should be restricted from non-commercial GA. I can modify my car or boat to my heart's content, but do so in an aircraft and it's suddenly a paramount offense.
Also, I have no idea what the purpose of the discussion of marine vs aviation expenses is. The marine industry isn't nearly as expensive as the aviation industry is until you start playing on the commercial side or are dealing with large vessels. A Cessna is akin to a 20' runabout, not a 30' offshore center console fishing boat. You can get a new 20' runabout with modern EFI engine for less than $30K, or you can buy the SR-22 version from Formula/Chris Craft/Cobalt for $50K. Either way, the parts are affordable because they're mostly universal parts for GM engines. You start playing with 350HP outboards and things are bound to get expensive. Also, the carbed boat and jet ski have had their issues with reliability from time to time, but the EFI outboards have never needed repair or adjustment.
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