I have the precise flight setup. I've never had to use it but, my sense
is that the vacuum failure light may be the most valusable component.

Blanche wrote:
Concerning the scan to recognize a failure...In addition to the
backup, Precise Flight also offers a lamp that is triggered by
vacuum pump failure. An immediate warning rather than waiting to
discover it. True, it doesn't offer any redundancy, but minimizes
the time to identify a problem.

Of course I recognized my AI failure immediately -- I was turning
right and the AI turned left....