I currently have the 27" i7. It was beyond perfect for the first week and then began flickering. I took it to the apple store (waste of time) and they installed the firmware, which as you all know does nothing. Since I have the case number established, how long can I hold on to this flickering machine before I send it back for a replacement? I want to wait until I know the issue is fixed before swapping them out. I'd hate to get a replacement now, wait 2 weeks for them to ship it, and it have the same problem.