Awaiting an iMac 27 and looking at external DVD drives and backup HDD. Many reviews of external devices seem to complain about cord length (some cables only 3 inches long). As I've never had an iMac, I find it irritating that manufacturers don't include the cord length. I'll get a USB2 DVD drive and USB 3 HDD. Anyone have any comments about specific drives that allow the use of the drive without it hanging in the air under the screen?