With the rise of USB and Firewire SCSI's going to become obsolete pretty quickly. It sounds like too much of a pain in the ass to bother using just so devices respond a bit quicker. I do know how to work with it in case I ever have to deal with it (I'm training to become an IT tech).
IDE here - SCSI is on the way out! Macs haven't used SCSI for years (ever since they released the first iMac back in the day). Everything (including the keyboard and mouse) uses USB connections now.