I'm guessing you've never owned a BK, in reading this statement.
When burned at any rate equivalent to what the PE can do, the BK will have similar flame show. It's not like the BK magically changes the properties of the wood you're burning, somehow suppressing flame that naturally appears at a given burn rate.
View attachment 300838
Yes, you can
also turn BK's down to "black box" mode, way below where any non-cat could ever possibly burn, but no one says you
have to run down there.
One of my BK's is run with flame show more than 60% of the time, at a rate that consumes 3 cubic feet of wood in 12 hours. I run the other (smaller addition) at a rate of 3 cubic feet per 24 hours, and that one is indeed black most of the time. You have both options.