+1 to the "use what others in your class use".

I have a DL1. While Traqmate seems to be prevalent in the SE, some very fast drivers with DL1 have shared data with me and its made me faster. I've also made myself faster with my own data. I almost wouldn't bother going on track without it. (edit: I mean in a test day. I don't think I've even looked down at my display during a hard race, but would probably rather not put wear and tear on the car on a test session without data, as I couldn't have quantitative evidence on what the changes to the car/driving did)

If I was in SM, I'd have Traqmate as the majority of SM people I've seen use Traqmate.

The other advantage of the DL1 is the ability to add the Dash2 system into your car, eliminating your gauges and all that crap in favor for a digital display.

-Tom