Given the option of either display, which would you choose?
Things to consider (disclaimer: I use a 27" LED, and I haven't used the 30" - although I've many seen good things about it)
- 27" has a glossy screen, 30"is (I believe) matte - personally, I'm OK with glossy and think the issue is swings and roundabouts, but its a deal-breaker for some.
- 27" has a mini DisplayPort cable that also plugs straight into Thunderbolt ports.
- 30" has a
dual link DVI input - to use that with a current mac with mini DisplayPort or Thunderbolt you'll need a MiniDisplayPort-to-
Dual Link DVI adapter. The regular MiniDP-to-DVI that you may already have is only single-link and won't support full resolution: the dual-link one is more expensive and needs power from a USB port.
- 27" has built-in USB hub, MagSafe 1 power supply, camera, mic and half-decent (i.e. better than in a laptop) speakers.
- 30" arguably has a better quality display esp. for pro graphics work and is something of a 'classic'. This means they've held their value so you'll pay (relative to age/condition) more. 27" is still a very nice display, though.
- You may want to look at new displays from third parties (e.g. Dell Ultrasharp range) rather than the 27" - they could be better value if you don't want the camera/speaker facilities.