I think the scales on the auto charge units are better than most of the stand alone reloading scales.I have a Hornady Auto Charge scale that I've used for the last seven years.Prior to getting the Hornady,I had RCBS 750,RCBS 1500 and Pact equivalent of the 1500.All the stand alone scales had a lot of drift.I think the auto charge scales are designed to reduce the drift because they have the final trickle feature that must be more sensitive and precise to quickly come to the final weight.I usually don't use the auto feature because I don't usually load a large number of rounds at one time,but I do use the scale itself a lot.By hand loading the scale,I have really noticed just how much better it is than my stand alone scales I've used in the past.As for drift to the nearest 0.1,you have to understand the amount of kernels of powder it takes to make .1 of a grain.Extruded powders are the worst because many times the kernels are not the same size.So say I'm using a short cut extruded powder,it usually takes two kernels to make .1 of a grain.So think of it this way,each kernel weighs .05 grains.That one kernel may put you on the low side of .1 of a grain or it may put you on the high side of .1 of a grain or it may put you so close to the next grain the scale just cannot decide which to settle on because most scales are accurate to plus or minus one tenth of a grain.This is where the more expensive lab scales are going to show you how close you are to the nearest tenth of a grain you are because they are reading to the nearest hundredth or thousandth.I really like the ball powders a lot because the kernels are so much smaller,it takes a lot of the tiny kernels to make one tenth of a grain compared to the extruded powders and the scale settles quicker just by adding or removing a few more kernels.
