Dependability: Most high-end SCSI hard drives are quite expensive but there are good reasons for it. They can sustain higher temperatures and stay mechanically functional despite the expansion of the metal parts with temperature and and generelly have better build quality. The net result is that they are the natural choice for enterprise server applications. Connectors suitable for hot-swapping drives in RAID-systems is something only SCSI boasts, and helps maintaining large disk arrays where down-time is unacceptable.
from
http://www.acc.umu.se/~sagge/scsi_ide/ seems a lil pro scsi biased and they dont give any reasons or facts behind what they said