My group has standardized on the etrex-20 ($168 from Amazon), ridewithgps web site, and OSM free maps. Sooo much simpler and cheaper than what I used to have to do. Even one of our 800 users is considering converting down to the etrex-20. The transreflective display is great in sunlight (brighter the better), don't have to touch the screen and get it all sweaty, --perfect device in my mind.
Not that I am considering buying one but what you said here is interesting. Can't beat the price. I'll assume you get no audible prompts if running a set route (?). This would mean paying close attention to the screen so you don't miss your turns if I'm correct. ( Do you still use a cue sheet? ) You also didn't mention how you mount it but that shouldn't be too hard to do.