I used to have 3 monitors for many years (2x21"/1x19"). (Well, actually I had 7 monitors for Nuendo/Cubase/Nuendo…). I recently replaced all that stuff with 3x21/9 monitors right after C6 to C7 upgrade and I have to say it’s a visual revolution… 2x21/9 for Cubase, full screen mixer on right side. 21/9 is just the right size for our horizontal timeline and to display a large mixer imo. Everything’s easier and way more comfortable here now.
About the distance, I feared about the resolution like Rhino said. Distance is about 100cm and everything’s great.