A digital scale that's sensitive enough to indicate 2 decimal points, ensures the accuracy of the common tenth of a grain powder measurement. That said, the more sensitive the scale is, the more challenging it can be to use it, since the indicated weight can be affected by extraneous forces. Repeatability is more desirable than the ability to weigh an electron just once in a while. If you put powder on the pan, and weigh it, remove the pan, then weigh it again, and repeat a number of times, the reading should always be the same. Some digital scales wander a bit after the indicated weight has stabilized; this isn't a problem provided you accept the weight indicated as true, as soon as it stabilizes. A digital scale should have leveling feet and a bubble level. A digital scale should be warmed up prior to use, and if the AC adapter is used as the primary power source, can just be left on all the time. A digital scale should have a warranty; mine is warrantied for 35 years and a GemPro 250 not a horribly expensive scale. Its common when using the 20 gram check weight to zero the digital scale that it won't read exactly 608.65 grs, but it should be close. Chances are the check weight does not weigh exactly 20 grams, I have two 20 gram check weights and neither weigh exactly 608.65 grs, nor do they weigh the same. Do not attempt to weigh more than what the digital scale is rated for, chances are it will damage the scale. The digital scale should not be dropped, shaken, or exposed to vibration. Use your kinetic bullet puller somewhere else.
Balance beam scales, in their better examples, are quite suitable for reloading purposes. Their accuracy is usually +/- .1 grain, so there is no point in attempting to weigh a powder charge closer than .2 grs. Balance beam scales should be kept free of dust. Balance beam scales are best when zeroed for the intended weight, this is best accomplished with a check weight set. The reason for this is that when the scale is zeroed at "0" the further along the beam you move the counter weight, the potentially less accurate the indicated weight becomes. Perhaps the potentially most accurate balance beam scale commonly used by reloaders is the Lee Safety scale. The beam only measures 100 grs along it's length, and it has no magnetic dampening, which can affect the repeatability of some scales. Using a balance beam scale without magnetic dampening is an exercise in frustration, which everyone should experience at least once. This makes digital scales look quite appealing.