Both are great cycling computers in their own right. Search the net long enough and you'll find people who've had trouble with both (I had an issue with a first-gen Bolt) and many more people who are happy with both units.
The Bolt is FAR easier to set up and edit screens, that's the big advantage.
The 530 without a touch screen is a little tricky, but it's a moot point once you've actually set the thing up.
The 830 has a very nice touch screen which makes editing data fields less of a pain.
Originally Posted by
WhyFi
Setting up the screens on the Bolt is easier/more intuitive, that's the major selling point that it has over the 530, IMO. Once you're beyond the set-up stage, though, I don't think that there's really an ease of use advantage.
^ Basically that.
You'd be happy with either unit. Choose the one you like the look of. I'm in the Garmin camp myself.