27 is really the max you want, 30 is way too much in your face even on the bigger desks.
Recommended viewing distance for a monitor is 18". At that distance, to comfortably see into the corners, I need to move my head with a 20 inch monitor. Forcing your eyes to take the strain of looking into the corners will cause strain on your eye muscles. Even more when you consider the correct height for the top of the screen, is eye-level. So seeing into the bottom corners is far too much, for eye movement alone.You dont need to move your head to look at a 30" monitor... unless you are about 3cm from it that is.
I sit around 36" from mine and it's great.
30" is way to big imo. 27" is a very sweet spot!
After using 30" for about a months or so now, I can't see myself going back to anything else. Obviously I can only speak from my experience but you get used to it after maybe a day or 2. Wonderful to use for just about everything.