Many years ago I did extensive testing of several manual powder dispensers, including a Harrell's BR unit. Multiple powder types (ball, stick, flake, etc.) were tested and throws measured with a lab electronic balance. I was quite surprised at the results as the hands-down, across the board winner was the red Hornady unit. Nothing special about it, no idea why this unit was superior. I sold my Harrell's BR measure.
I will say that my Chargemaster 1500, with modified programming to slow it down (NOT speed it up as most guys do) and restrictions on both the intake and output orifices, measures VERY precisely, far better than any manual unit. (Again, checked with literally thousands of throws.)