Separate FX send per L/R input.
It’s already very cool that you can centre L and R inputs, essentially getting 2 inputs.
It would be awesome to be able to adjust FX send for each (or even just bypass FX entirely for one).
Then you could bring in e.g. a drum machine on one, clean, and a synth on the other, using the great effects like delay, without muddying the beat.
A possible interaction model would be push-and-turn on the send knob, to adjust the R send only.