I use the LT-6000 and really like it. Works as advertised and the data logging is quite good.
Down sides: is only accurate to about +/- 0.2, but honestly not like us club racers are trying to qualify for F1.
Also, the software and interface aren't the easiest to use.
But for $400 and gives you real time lap times in the car plus green/red projected times on your lap your doing, it is a great tool.