Almost everybody uses the Garmin because there are few alternatives, not because it's better. Probably 95% of the ANT+ bike head units out there are Garmins. They generally work, except some people seem to get lemons, or get their data dropped the day they went for a PR or whatever. Personally I've never had a problem with a 500, though I did briefly have a 510 unit that was dropping data consistently, which I returned for a 500.

I think ygduf tried to go off the Garmin reservation, not sure how that worked out.