We have the Street Pilot 2610, we just got it a few weeks ago and LOVE it. It's the best thing since bread came sliced.
It is not, however, suitable for caching on its own as it does not have any battery backup. If it's not in the car, it ain't woikin. Plus, I am guessing, after having had a Street Pilot III before this one, that it would not get a strong enough signal in tree cover, and you would not get such an accurate lock.
We use ours for caching and would be lost without it, but when we get out of the car, we fire up our handheld Magellan Explorist.
Happy caching!