I recommand the Velocitek S3 http://www.velocitekspeed.com/.

This is small company (but great product with 2 year guarantee) in the US company based on Oregon River. The GPS as a great display, big, readable, precise and refresed every sec. Each movement, tunings you do that has an impact on your speed in instantly displayed...

Big advantave vs other is that you share data with your partner.

On the top of that, this GPS is waterproof at 25m.