My RCBS Chargemaster works great with Varget. Yes, you will every once and a while get a charge over by .1 or .2, which you will be alerted to by the Chargemaster itself. Think about 2-3 out of every 100 charges will be thrown over your desired charge weight.
I also find that when the Chargemaster sits with powder in it for a period of time, the powder gets more compact, which causes the erroneous overcharge in the beginning of a reloading string.
I love the Chargemaster. I cannot imagine a better system out there for reloading by weight.