There were some gotchas on the 480/Dynon interface. Email or PM me for my complete wiring matrix for Dynon D-180 / GNS 480 / GPSMap 496 / TruTrak Digiflight II GSVG, may save you some time.
That said, the biggest differences between the two are:
- 480 is less popular, runs about $1,000 less than a 430W but has even bigger difference in resale (people don't understand the 480, so will offer less for your plane).
- 480 has IFR airways; you can enter your flight plan exactly as ATC gives it to you (e.g. "fly direct Alpha take V-1 to Bravo, V-2 to Charlie, Direct ..." etc.). It automagically fills in all of the points in between, which has gotten me yelled at with a 430 when I missed a point that made a dog-leg. Pretty unimportant away from the heavy traffic East or West coast busy areas; a life saver if you fly up near New England. If you only fly VFR direct, skip it.
- 480 will, with the right autopilot, fly the entire approach coupled to glidepath and then at the push of the button fly the missed approach and then put you in holding. Try that with a 430/530...
Good luck!