Imagine then, having a 3u tuner RE with four displays sitting at the top your rack.
A guitar and a bass both plugged in, you pick one up, and boom, tuner. The tuner also works when the track is playing back.
And it's pretty fast and responsive (this is the GVST GTune I'm talking about).
And the the other two are monitoring your piano, organ, synth, whatever, while they play back. Admittedly there are display devices like this in RE format for MIDI
It would be pretty cool.