I'll put in a strong vote for the 520. IMO the 520 is the 500 with all of the bad features fixed. You can load very good open source maps, which makes the mapping very good. The other major upgrades from the 500 are wireless uploading, which I wouldn't have considered a big deal but now I wouldn't want to live without, and the ease of customization. The 500 annoys the heck out of me how it has fixed size arrangements for the fields. Like if you want 5 fields, you have to have one big and 4 tiny.