[tmcb]

> Doesn't the inclusion of the digital accuracy checkers then decrease the efficiency, and mean you might as well use a completely digital computer?

Not really. Whatever output the analog computer returns can be digitized with no detriment to its performance, pretty much in the same way a sensor which measures a physical property can have its output fed into a digital system with negligible interference over the original measurement.

Also, the same rationale can be used to probe intermediate steps and automatically check for their accuracy, even if only during validation phase. This is a possibility that was definitely not available, say, 60-odd years ago.