(lurker from FL posting 🙂 )
A newbie in my office just got the eXplorist 500. I was very impressed. I started with a Magellan Sportrak Pro and graduated to a Garmin 60cs this Christmas. I love the auto-routing features of the Garmin, but the 500 has some features I really liked: the expansion card, the file system for organizing waypoints on the unit and I’m pretty sure it also gives you more waypoint info right on the unit, like cache size and even the hint. Not sure about the last, but I can check.
I can’t understand in a million years why they didn’t put usb ports on the lower level units – I mean, how dumb is that – but the 500 and 600 look pretty cool.