What we thought: We use the RR for all of our track events. It records laps and split times easily. The case is made of a sturdy rubber, but it comes apart with a tug. Thank goodness it goes back together easier then a Radio Shack remote. The big complaint is the programing, is almost too simple. Computer geeks will not like this, but tiny race car driver brains will comprehend the programing quickly. After each road corse run you need to save it, or your laps will be erased. After learning the programing quirks, the lap timer is insanely accurate!! we put it threw some paces at the 2011 LS fest. The GPS is so accurate it recorded our auto x runs on the in-field of a tiny circle track. we also use this as a speedometer while driving on the street.
PROS: If you love track days, this will make you love them more! The GPS works like a charm anywhere.
CONS: Software is behind the curve. the screen reminds us of A Game Boy