Heres what i know:
You're talking about auto-routing. Step by step directions, right? Because the Explorist 210, 400, and the vista, and legend don't have that. That leaves you with the most expensive one, the Venture CX.. I'm not sure how waterproof the Venture CX is, but the magellans are for sure. So the question here is, do you want durability, or autorouting? So unlesss you want to shell out the dough for the Venture, I think that all the other gps' would do what you wanted. I have a explorist 400. It works great, has good maps, (topo too), is waterproof, and durable. I've dropped it quite a few times without giving it a second thought. I also have a Etrex Vista. Because it is a friend of mines GPS, i don't take it on adventures where it could get damaged. That gps also seems to work. Also, Magellan or Garmin.
Oh well