I have a Garmin Vista HcX. I tried it out on my ride on the Lewis and Clark trail this summer. I found it to be moderately useful. I tried to use ACA's waypoints and found them very confusing. There were thousands of them, many of which didn't apply to me. I was madly trying to figure things out and load routes in the days before I left home.

On the road the routes didn't help that much. I think the maps were more useful. One way the gps actually confused me was when there were bike paths. Garmin's mapping software didn't have them, so it would try and route me onto roads next to the bike paths. Instead of being helpful, the gps made me more confused. I would have been better off just using the ACA map. However, the ACA maps can be confusing as well. They cram a lot of info into a small space and it can be difficult to interpret. Also, once I found the ACA route description plain wrong. In Umatilla, Oregon the description of how to go under the freeway, turn left, and get onto a bike lane was wrong and sent me on a wild goose chase onto dirt powerline roads that deadended.

I did find the gps helpful in finding things in towns - restaurants, libraries, car rental places, motels, etc. I'll probably bring it on future tours.