What are you trying to accomplish? What do you hope to gain by timing your laps? Personally, on the track, I judge my performance by line and consistancy.
What are the insurance implications of doing so? Most if not all policies are void if timing is involved. Timing is forbidden at Audi events for just that reason.
My biggest issue is what do they tell you? If one lap is .1 seconds faster what does that tell you? I don't think I am a good enough driver to be able to tell you in which of the 573 motions I made during that lap which one caused that .1 seconds.
I'd probably get one of the acclerometer based ones where I can actually tell where something was different.
I realize some people are just concerned with how fast they are, but that just isn't me at the track. Now at autocross....
