Have been using the same RCBS Uniflow since the early 80s. I know it came with both drums, but I don't think I've see the pistol one in 30+ years, I never used it.
I had the Lil Dandy rotor thing for a while might still have it somewhere, also haven't used it in decades. Had several of the rotors but none of them ever dropped the charge wt of the powder I was using, that I wanted. Over, under, no problem...
I have used the old Lyman No 55, tis a good measure for many things, and it has a knocker
Used a Redding back in the 70s too, but the hopper got broken during a move long, long ago.
My uniflow has worked just fine, all the way down to loading .32 acp with the powders I use. Never leaked anything I use. Never used HS-6 though, so I can't say for certain. Bullseye, 231 Unique, 2400 and 296 are my usual pistol powders. Have used the "Dots" on occasion, no leaks with any of those.
Bought mine back when they were about $30, its been my "gold standard" ever since.
There might be better measures out there, I don't know, not looking, what I have works great.