Great as far as brevity is concerned! I think I would mention about the GPS accuracy: "10-to-30 feet AT A SINGLE POINT..."
Naturally, when you get more than one point (Which GPS' take on the average of every one to two seconds, right?) the accuracy issue is further confounded.
But, for the benefit of the 'garmin geeks' (God, I love that...I need to borrow that for a blog post!) the 10-to-30 should work fine.
A tip of the running cap and the beer mug in your general direction, Pete.
(I was in a conversation with a non-running friend the other night, who understood the GPS/shortest possible distance limitations right off the bat. If a non-runner can understand it...?)