I have one and it has been a really good tool. Everytime I buy a new set of packs, I run them through this. As it discharges the pack it gives you the volts and amps every 15 seconds. In the end it gives you the overall run time of the pack and the average voltage.
What this allows me to do is rank the packs from strongest (packs that I use in the main) to weakest (practice packs). I compare the packs output at 60 seconds, 120sec, 180...
I wish that I could of got mine at that price...Ouch!