"John T." writes:

Remember that there are likely additional charges to the $1495. A
new antenna to receive the WAAS and possibly a new RF antenna cable
with lower loss will need to be installed.

Indeed. My local avionics shop estimated more like $4000 for the
whole deal.

Much new hardware inside (for whatever that is worth)
Addition of a decent terrain warning map

(That was already available for about 1 AMU as a separate upgrade for
430/530's.)

Much faster updates to track (maybe 5 Hz)
This last one might be of use in IMC with gyro problems.

Dunno. Digital numbers won't be readable at 5 changes per second.
Analog outputs are basically just CDI/VDI's, whose super-rapid updates
may help only during the tail end of an approach.

- FChE