I'm on the steep part of the learning curve with my DL-1 but here's what I think I know at this point...

The system resolves both the GPS and internal accelerometer inputs and, if the track trace is to be believed, it is accurate within a couple feet. I could identify the lap that I dropped the left front tire off the outside of Oak Tree at VIR, as opposed to the ones where I just rode the edge.

I took my car for a drive on the street to do the coast-down tests necessary to program the system that computes engine power and was putting some big wobs into the wheel to see how the rain tires' grip peaked: I could SEE the lateral acceleration trace get fuzzy where I put in too much steering and the cold front tires scrubbed the pavement rather than just gripping.

I'm not entirely convinced about the "best theoretical lap" thing simply because, depending on where your segment breaks are, you might have to give up more in an adjoining segment, that you gained by optimizing just one.

As I said, I have a lot to learn - both about the system and my driving - but I am absolutly convinced that data helped pretty much all of the drivers when we did the VIR enduro.

K