SCSI is no longer required by the average user, as BurnProof and UDMA has rendered SCSI's advantages in those areas null (the cost of the SCSI card and the "extra fee" for the SCSI drive itself also led to SCSI-optical's death). There really is no need for SCSI burners for users nowadays, and that's why the SCSI burner market was stagnant for so long (the last SCSI burner Plextor released before their current 40X burner was a 12X model). I predict this 40X will be the last SCSI drive Plextor ever releases. The only true need for SCSI burners are for enthusiasts with more than 4 IDE drives and CD duplicators/towers, which benefit from SCSI's command queuing, multiple IDs and extra buffers that the drives have. If you want the best CD burner right now, the Plextor Premium is the one, IMHO.
Drives I Own:
Asus S520/A, Plextor UltraPlex 40TSi, Lite-on XJ-HD166S, Pioneer DVD-106S, Toshiba SD-M1712, Plextor PX-R820Ti, Plextor PX-W1210TS, Plextor Premium, Samsung SM-352B, Teac CD-W540E, Yamaha CRW-F1, Plextor PX-708A, Sony DRU-510A