I have one. Nothing more than an expensive powder dump. I choose to weigh every charge on a balance scale I would say it is right on about 30% of the time. The remaining 70% is over by .2 to .4 of a grain. The pulse sent back to the dump from the scale is slow enough for the dump to drop extra granulars causing over run. You can get by this by setting up the dump to dump .2 to .3 under your desired charge.
It is nice to have the powder dumping though when I am seating a bullet.