I found several reasons to prefer the GNS 480 over the GNS 430W. I was
hoping to get some specific feedback from the group about the two units,
rather than just personal preference or anectodal comments. I've worked with
the software simulators for both and have studied the downloadable PDF
manuals and literature. I have prepared my own list of factual differences
between the two units and my comparison leads me to favor the GNS 480.
Here's my current comparison list below. Perhaps those of you who have a
chance to fly with both can provdie additional points of comparision between
the two (GNS 430W and GNS 480) and double-check my work. Since the software
and feature set of the GNS 430 was changed in going to the GNS 430W, a
comparison of the GNS 480 with the GNS 430W may be difficult, because few
have had a chance to really explore the GNS 430W new features.

Here are my specific comparison points:

1. Using the software simulators for both units, I felt that the GNS 480
user interface was easier to use and easier to update when a change to the
planned flight plan was required. See also the review article
http://philip.greenspun.com/flying/garmin-gps. In my simulator experience, I
prefer the "soft keys" of the GNS 480 rather than the pop-up menu selections
of the GNS 430W. The soft keys make many procedures easier to accomplish in
the GNS 480, and fewer button clicks are needed. I don't mind the FMS-like
structure of the GNS 480 user interface and feel that it will be easier to
master and use in a single-pilot IFR environment. (My unit is going into a
Beach Bonanza with S-TEC 50 and GPSS.)

2. The GNS 480 can provide full guidance through a hold, and can easily
accept ad-hoc holds. See the following article for information on how this
is done using the unit. When coupled to your autopilot with GPSS, the plane
is automatically flow through the entire hold.
http://freightdogtales.blogspot.com/...h-gns-480.html

3. With the GNS 480 you can listen to both NAV frequencies at the same time
(Approach and ATIS, for example) or both NAV frequencies. Only one unit is
needed! That's not the case with the GNS 430W.

4. The GNS 480 includes the Victor airways. Almost every one of the IFR
clearances that I receive includes a Victor airway portion, and these have
to be manually entered, turn by turn, into the GNS 430W.

5. The GNS 480 provides audio prompting when reaching a waypoint, when the
localizer comes alive, at 500 feet above the runway, and at the missed
approach point. See http://www.garmin.com/products/gns480/voicePop.html. The
GNS 430W does not provide any audio prompting.

6. The GNS 480 can control a remote transponder. So no panel space is needed
for the transponder if you use an appropriate unit like the GTX 33.

7. With a GPSS the GNS 480 can fly the aircraft through all approach
procedures, including DME arcs, holds, procedure turns, etc.

8. The GNS 480 provides a NAV page with a full compass rose CDI depiction.

9. The GNS 480 has a physically larger screen than the GNS 430W and higher
pixel resolution. The GNS 480 screen refresh rate is much faster than the
GNS 430/530. The GNS 480 screen is nice to look at and easier on the eyes
than the GNS 430W.

10. For IFR navigation, the GNS 480 appears to provide more assistance and
more capabilities than the GNS 430W. Perhaps this is what people mean when
they say that the GNS 480 is more FMS-like than the GNS 430W.

Have I missed any features? (Note, that I am considering the GNS 480 to be a
full Gamma 3, TSO C146 certified box, because Garmin will resolve the
current SAIB issue by the time I install the unit. So we don't need to go
through that discussion as part of this message thread.)