So I have both. I have the high-res 15" MBP, and I also have the 24" cinema display. You definitely notice the less pixel density. But I think your question is more around "can you fit lots more on the screen?" And to that, the answer is not really... Of course by having two monitors I double the amount of screen real estate I have, but as far as just comparing how much I can put on the screen of each monitor, it's really not that much different. Of course, with less pixel density on the 24"er, it's much easier to read from a few extra feet back.