[SPS]

We have used one for 4 or 5 years with great success,
as Ed said, the Tachfacts software is easy to use and the information gained is as good as having a Racepak. (I've had both)
The Autometer people are great to deal with if you have any questions or problems. (Had an issue with Windows Vista at first, but they helped with that)
In addition to Ed's comments about the driveshaft speed, its worth buying either a Mark Williams or Strange pickup collar. Makes things cleaner and easier to hook up.
Also, the ability to download, store and overlay any runs will be a big help. You can also blow up a certain area for details. The converter slippage is shown as you scroll across the graph. Also, hook the trans brake up, and it will show exactly where the car leaves.
Victoria sets the tach after the burnout to start it. The memory has the ability to "back up" or show data before its set to start so its easy to get a whole run without worrying when to start. It automatically stops taking data at a preset time after a run so no wasted time.
It also stores 5 or 6 runs at a time so it is not necessary to download a run each time you use it.
Great value for the money, we feel.

FJ