Digital HP/TQ meters--worth it?

I've seen those digital HP/TQ velocimeters on sale a few places and wondered if they are worth the $$$, and really work? Would this be a usafull tool, or a waste of $$$???

can you get to the track all the time?
are you going to be doing many mods soon?
IF you cant get to the track and are going to be doing mods and want to ballpark whats going on.. then a G-Tech or other accelerometer will help you. but its only as good as the road you are on.. best to have them on long flat roads that are very even..

The newest G-Tech is what I would try out with the computer linkup.

JMO, but anything I can hook to my PC and look at data is better than sitting in the car reading it..