I didn't wear my GPS last week when I ran the 12k, and I have mixed feelings about it. I'm not sure how accurate it would have been, but I would have liked to compare and find that out in a safe venue. I would have liked the detail to review the speeds I was running at different course profiles (how fast was that hill, how fast was the downhill, how did I do on the flats). I would have liked to be able to push the pace from the start, then gradually increase pacing as the race went on - I often find that at the end I think I could have pushed miles after the first 1 or 2 to make up a little extra time. At the same time, I am somewhat afraid it would have either encouraged me to work harder or held a less sustainable pace.

Bottom line, I think I'll wear it next time and see how I like it. As with my HRM, if I find it frustrating in a race, I can just pull it off or turn it off and still measure time and press the lap button for distance at each mile marker.