Big John wrote:

I also was throwing in the head movements to look at GPS (where ever
it is mounted) and then instruments on panel with the high probability
of vertigo.

If an IFR approach certified GPS requires extensive head movements
to follow the CDI, something went badly wrong in the install. The
CDI for an approach GPS should not require more head movements
than looking at any other CDI. In many installs, it *is* the same
CDI as nav radio.

Also the communications required on a IFR instrument
approach divides your thought process and raises the difficulty.

Very true, but wouldn't this apply no matter what approach is
being flown?

Cheers,
Sydney