In article ,
Ron Natalie wrote:

Why would the EFIS be any different than an HSI (or as Bob already
posted the 707 RMI). It still has a heading which ought to be
verified with some real reference (Whiskey compass or runway).

It is verified, by two redundant computers that will set a warning flag
if they're off by more than a few degrees. (4 degrees in the plane I
fly.) If either gyro isn't tracking correctly, or isn't agreeing with
the actual magnetic heading (sensed by two independent flux gates), the
warning will trigger the second the airplane makes its first turn on the
ground.

This system provides MORE accuracy and MORE redundancy than correcting a
manual DG to a whiskey compass, and frees the crew to check the myriad
of things that do require human interaction to verify before flight.

Now that I have a slaved HSI, it's almost always right so I could see
forgetting to check it.

These airplanes have more than a slaved HSI. They have two (or more)
separate, independent remote heading gyros, slaved to two (or more)
separate, independent heading sensors (flux gates). If anyone ONE of
those 4+ systems reads differently from the others, a warning will trip.

I think you guys are barking up the wrong tree here. This isn't a case
of losing redundancy, it's the case of an automatic system being able to
do a better job than a human at this particular task. (Do you think an
old-style, manual variable-pitch prop is a better system than a
constant-speed prop, because it keeps the pilot more involved? I sure
don't.)