How does Studio One do it, exactly, can you explain, or do you happen to know of an article or video that demonstrates? I had a look at the time sig and metronome sections in their docs and don’t see any mention of automatically showing compound time sigs’ tempo differently. And if it’s automatic, how do they supply the option to “turn it off” for when 6/8, 9/8, and 12/8 are not meant as compound sigs.
That said, a nice feature in Cubendo would be that the little quarter note icon in the transport be transformed into a pop-up menu wherein one could choose any note value upon which to compute the tempo.