2x19inch lcd: 2x1280x1024 30inch lcd: 2560x1600 2x1280 = 2560 therefore 2x19inch lcd: 2560x1024 30inch lcd: 2560x1600 =========================== 2x20inch lcd: 2x1600x1200 30inch lcd: 2560x1600 2x1200 = 2400 therefore 2x20inch lcd: 1600x2400 30inch lcd: 2560x1600 =========================== you should able to tell the difference at this point w/o further calculations... if you don't trust me, you can put those numbers into the google search box & bam!! i wish you well in the future.... & pekelo there's nothing wrong with american public schools... i'm still in the 17th grade.
For charting, I'd probably still prefer 2 x 19" at lower res for the greater total screen size. Put 2 equal-sized (in inches) charts side by side at different resolutions and you won't see that much difference, so you can fit more on a couple 19" than 1 30" I think.