I've used a 305 for the last 3 years and a cycling buddy has the 705 which he used for most of last season. I recently purchased the 500 based on his/my experience. My friend never uses the map feature, but does use the turn by turn notification. I felt this was a useless feature (for me, YMMV) because I am intimately aware of the roads all around our cycling area (I map out all our rides). I can see the map benefit if you are using the unit in an unfamiliar area or you travel a lot. I will say he has more of a tendency to be caught looking at the unit vs paying attention to his riding, whereas I focus on the ride and only refer to my computer when I need to.
So far I like the 500 with only a few minor reservations:
- Glare off screen from certain directions (wish they would come out with a matte screen cover like Apple iPhone)
- They took away Sunset/Sunrise Data Field - I used that a lot on the 305. Seems they could add it back in future firmware version.
- Max HR has to be set in Garmin Connect, then sent to device
- History is a little funky - you have to reset it to view history on the last ride. I think I'll get used to this - it's just different.
What I like better:
- The 500 is smaller, lighter (big woop) by about half
- It has better screen customization - 3 separate screens, up to 8 fields per screen. This is a fantastic feature.
- Better retention system. Anyone who has had a 305/705 will tell you the mounting was a weak point. They supply lots of spare bands with the unit, too, so you can carry a spare with you in your seat bag.
- I find the backlighting is better. Only important in low light, night riding or indoor computrainer classes.
- Battery life is fantastic, just like the 705 - you don't have to obsess about it like you do with the limited battery life of the 305.
Bottom line, if you don't need/want maps, the 500 is probably the better choice.
If you want an exhaustive review of the 500: http://dcrainmaker.blogspot.com/2009...th-review.html