Ghengis,
I bought a 500 a few months ago - can't fault it. One really "neat" feature is that, when using it in a car, it will actually (try to) read the road names - "Turn right on High Street".
When I bought it I also got:
- A hard carry case
- A spare battery and mains charger
(I've never needed the spare battery - I usually manage to power it off the aircraft electrics)
You can find the manual for the Aera range at:
http://www8.garmin.com/manuals/aera500_PilotsGuide.pdf
As far as the difference in Terrain Mapping: I don't think it will make any difference - unless you are trying to fly down valleys with it. I knew I had seen some numbers giving the difference - I finally found them on the Transair web-site:
500 "with terrain/obstacle data shown at standard 30 arc-second resolution, you'll enjoy a surprising level of detail on the display"
550 "Terrain/obstacle data shown in higher resolution 9 arc-second detail"
Hope that helps.
OC619
P.S. It's great doing PFLs - "Terrain ... Terrain ... Pull Up ... Pull Up" in the background
