Our Nuvi 750 is the only GPSr we own and it works really well for us. We use it in automobile/3D map mode to get to the cache location and then use it in pedestrian/north up map mode to find the cache. It works pretty well for us... the only reason we would consider needing an additional unit would be so I don't need to deal with Ben going off in random directions because he trusts his geosense more than my ability to follow the coords lol

Features we love:
1. We keep all Maine caches loaded and have the Tour Guide turned on so it bings at us as we approach caches.
2. The Routes feature lets us choose 25 points and have the Nuvi optimally re-order the route - either by faster route or shorter distance.

My only complaints would be:
1. The internal battery means when the battery drains we're done caching. We could not finish the Sears Island caches because our battery drained when we were at the halfway mark.
2. Switching back and forth between modes is a pain, but it is not necessary for all caches so the nuisance is fairly minor.