I decided to purchase the Acme's for my custom build 300B monoblocks some time ago after doing extensive research on all the top line 300B tubes, really became a crap shoot as all the nice 300B's have their proponents. My take is they're all nice and you'd likely be happy with any of them. There are instances of premature failures in some of them, but in most cases limited to certain amps. For instance I did find a thread with a few Acme failures in LIne Magnetic amps, bad batch of tubes or excessive plate voltages in the LM amps? Don't recall seeing more recent failures of this tube.
Anyway, the Acme's were a substantial upgrade over the Shuguang Black Treasure which based on reviews are likely the best of the lower grade 300B's. Far greater resolution and transparency, greater harmonic development, timbre far more natural than the Black Treasure. I'd judge flavor as neutral with a touch of warmth, the warmth coming from the harmonic development, just right in context of my total system. I wouldn't want to go further in warmth, I like articulate bass without bloat.
I consider a top line 300B tube as mandatory for any equipment using the tube, really not hearing near it's full potential with the lower grade 300B's.