Considerations when connecting an 11" 2011 MBA and 13" 2012 MBP to a 2560x1440 Dual-link DVI monitor

It should be fine. Apple themselves offer to sell you a 27" display along with the laptop so it clearly is capable of driving that many pixels.

I myself use a 15" 2012 MBP Retina with one of those mini DisplayPort to Dual-Link DVI adapters (hooked up to a Hazro 27" monitor, so cheap no-frills much like you're considering) and its been pretty good. This is in addition to also driving a cinema display of the same size, so I have two external monitors.

I read a lot of reviews around the Internet before buying it, and there's a few horror stories (most of them say make sure you get one with firmware 1.03, but there's no way to tell what firmware you have, till you plug it in! - fortunately mine was 1.03 from the off).

The only issue I have with mine is occasionally (maybe once or twice a day) the Hazro monitor goes blank for a second, then comes back on. I have no idea whats causing this, the MBP doesn't even notice (doesn't try to rearrange windows or anything) and its infrequent enough that I just live with it. It may be a slight incompatibility between some of the equipment.

I do suffer from some occasional oddities if I unplug the external monitors while the MBP is asleep, then wake it up (the internal screen won't come on, I think its the graphics card drivers crashing at the unexpected situation) but I don't believe thats related to the Dual-Link DVI.

I use a 11" 2011 MBA (i7) with an Apple Display with a resolution of 2560 x 1440 with no problems, so you shouldn't have any problems with it (My previous monitor was an HP 27" with DVI and I used the MiniDisplayPort-To-DVI adapter.

The only reason why I changed to the Apple one is because this was brought by the company I work for :)