I've used a Garmin 520 for about 2 1/2 years now. It's worked flawlessly for me, but I know others haven't been that lucky. Being a gadget nerd I bought a Bolt a couple of months ago. I had a lot of issues with the unit dropping sensors during a ride. Customer support walked me through some fixes but it was just never that reliable. I also use the unit for navigation and turn by turn directions. The color screen on the 520 is much better for this kind of use than the Bolt. In the end I returned the Bolt and went back to using the 520.

That being said, I ride with 5 or 6 people who bought the Bolt and love it. I say go for it, and if it doesn't suit you return it within 30 days for a refund or credit.

Tom