ArchAngelCD,
The 750 works great, and will run on a 9 volt battery if you want to sit (let's say) at the dining room table to weigh charges rather than where you normally have it set up and plugged in.
It has remained accurate for the 4+ years I have owned it, and I simply turn it on when I want to use it. I do not calibrate it every time as RCBS says to do in the manual. The display shows "0" when turned on, and if I remove the pan, mine reads -69.4 (these are the same readings I get if I go through the calibration steps). At first I was a bit cautious about using the scale this way, but I have tested it several times with check weights after turning it on and not calibrating and found that it was dead on every time. As a result, I trust it much more than when I first bought it, but as with every scale, I still test it every so often. My beam scale remains in the inventory in case of emergency.
However, any scale (including beam scales) can be affected by electric fields. I keep my beam scale covered with an inverted rubbermaid container, and the static electricity that sometimes build up will cause a dramatic change in the beam as I lower the container over the scale. Remove the container and the pointer returns to the same reading as before it is covered. Fluorescent lights can do the same.
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