I have one of the Pact scales, had it for about 6 years now. I thought that it would be a good scale, but it has been somewhat of a pain.
It was not functioning properly, so I called Pact, they said that the reasons my scale was acting up is because 1) I have flourescent lighting, the scale doesn't like that.
2) I use a cell phone near it, it doesn't like that either.
So I tried using the scale without the lights and my cell phone away from the area. Problem solved. However, the AC adapter has to have almost a dedicated outlet as it will make the scale fluctuate if not. I switched to the 9v battery, again, problem solved. Keep fresh batteries handy though as it goes through them fairly rapidly.
One other thing, it needs to 'warm-up' once turned on for a few minutes, the issue there is if it's left on too long, it shuts itself off, which is a good feature to save battery life, but bad if you take too long to use it and it shuts off before you make your first weigh.
I also still have a balance scale to verify the electronic Pact every once in awhile.
Just my 2¢.