For just a sanity check, OSM maps will be just fine.

I have the 800, and while I find that it's great as a bike computer/training aid, it has the most amazingly rotten route calculation capability of any GPS I've ever owned, bar none. One the few times I've used it that way, it tried to turn a straightforward three-mile ride into a 12 mile adventure on the New York State Thruway...