One caveat on the 30" 2560x1600 screen: I work with a single one but I found that I couldn’t place it farther than 3 feet from my eyes because small GUI VST plugins and VSTi’s were too hard to read. So I had to place my speakers on high stands to have a clear line of sight to them. Of course, everything is relative to the size of your workspace and the priority of your work: for a composer like me, it’s less critical but for a full-time tracking and mixing station, I would definitely go with multiple low height screens.
I believe a lot of factors need to be considered in this matter: the priorities of your work, the quality of your eyesight, mounting distance, line of sight to speakers, pixel size vs number, etc… IMO, in the end it’s a complex and personal consideration.