I've been using the Garmin 530 with the sensor package for about a month now. It was a great purchase. The sales guy at REI recommended the sensor package and I'm glad he did. I live in a hilly area and it's nice to be able to see at a glance what my elevation gain is as well as my heartrate. The dashboard has several fields and you can configure it to what you want.
I’ve had this for several months now and I’ve put it through mountain and road biking. It’s a wonderful unit and I highly recommend it to anyone.