Late to the fray again
I have two (2) laptops set up, each having a 2nd, 24" monitor. One machine, a 17", is the work machine. The other, a 15.6", is a documentation, reference, email, research machine. For instance, when I'm working on Web stuff, I'll have PHP documentation up on the 15" screen, JS (or other) references up on its 24" screen, as well as a browser for researching issues those docs do not reference or resolve. The 17" laptop screen will have some IDE up, often two (2) or three (3), while the 24" screen for this box will have, usually, several browsers up to check output, as well as other reference material - myBase, WikeNotes, Ultra Recall, gbCodeLib, Source Code Library, and the like, to let me reference various snippets I may have acquired.
When I have occasion to travel - the 17" machine is the traveler, in spite of its weight - I tend to feel very cramped and shut in with just the one (1) screen
Methinks there's no possible single monitor/screen configuration that could do what I'm accustomed to doing. Even the old four (4) quadrant plasma screens I used at some previous jobs don't hold a candle to what's here right now.
Sidebar: When I get my new external video card unit, I'll have up to four (4) monitors hooked to one machine. Downside to that will be, of course, RAM and CPU limitations on that machine - a significant consideration when thinking of multiple monitors with multiple applications running from one (1) box.
All things considered I'd say multiple monitors, no matter how small, will outperform a single giant one (1) every time.