I recently bought a 21 inch iMac (2012). I'd like a bit more screen real estate but have always preferred a two monitor setup to one giant monitor. In any case, I'd like to buy a 21 inch monitor that is as close as possible to the 21 inch iMac. A 21 inch Thunderbolt display would be perfect, but I don't see that in Apple's plans. I don't really care that much about the aesthetics of the monitor but just want to get the same screen. Other than the 1920x1080 resolution and IPS, are there any other criteria I should consider?