I have one of the older ones, scale on the side, made by Pact for RCBS and it is all I will use. Once in a while it throws a little under/over but rarely and I don't mind because I weigh every thing on the beam scale before I drop into the case any way, I load for accuracy only. The last loads I ran over the Magneto were 6br Norma and I had an ES of 9 fps over 20 rounds.
So IMHO it works.
PS I only turn off the scale I leave the Chargemaster turned on and recalibrate first every time. Also beware of fluorescent lighting, drafts from fan or A.C. and some say cell phones. I think an in line filter corrects all of these.