To be honest, I couldn't care less about polyphony in a tuner. It's nice on-stage (I use a TC PolyTune), but in the studio it doesn't matter to me.
If any change were made to the tuner, I would rather it be made easier to read, with lines for cent increments, more precise, faster and more stable tracking, and, like my own FR, updated to match Studio One 3's look.
As it stands, the tuner does not track very well, so it's extraordinarily hard to determine whether the tuner is displaying the actual pitch or tracking the wrong harmonic. The bar is too thick, with no segmentation or scale divisions to indicate where it is, and the strobe mode refreshes so slowly that it doesn't actually work as a strobe tuner, because at times it's near impossible to tell if it is stable and losing tracking some or if the note is that far off of pitch.
I hardly ever use the tuner plugin over the trouble of wiring in a hardware tuner, and for all of these reasons. Not that it's not polyphonic. It's just not usable.