Fair question. My urban canyon experience is limited, however crawling on my belly in Florida swamp is not. My Oregon changes it's mind constantly in tree cover. Even if you set it on the ground, it will vary 3-25 ft. If doing a slow creep, lets say 400m., your trail looks likes your signing your name through the bushes. I'm only saying the 60 seems to be more constant. In the open they seem to be equal.
My point however is, I have had my gps stop working at the worst time possible. Not geocaching, but operating a fuel oil barge across the Gulf of Mexico. It happens. That's why I have three aboard at all times!
Best regards.
Capt. BP