> In fact I'm going to reveal a secret : physically, desktop SATA drives are exactly the same as professional grade 24/24h operation-guaranteed SATA drives. When they fall off the assembly line, they're tested for reliability and performance. Over a certain threshold, a drive is deemed professional and receive the pro firmware; under the bar, it's a desktop drive.

This may be true in some circumstances, however I have observed that enterprise drives from some vendors have a larger heatsink volume than the consumer drives, and also weigh a little more.