well back onto the question SCSI or IDE:
currently there is no Plextor SCSI drive that offers 12X10X32 (I think). so burnproof could easily come out on their next SCSI CDRW drive.
second, with IDE, you take up one more precious channel (if you seperate every IDE device on their own channel like me). so if you want to copy from both a CD or from the HD, you best be able to have each on their own channel (only one of many reasons why SCSI is generally better).
finally, if you are on an full SCSI system, then it will be much harder to get buffer underuns even withOUT burnproof, because the HD isn't limited by the CPU (say you were playing a game or something).
currently it's pretty much a stalemate, but if I were you, I'd try to go all SCSI. perhaps later Plextor will have a SCSI CDRW with burnproof.
Finally, if you NEED a CDRW, and want SCSI right now, then that Yamaha burner will not steer you wrong. it has 8MB or RAM onboard.
their drives are of equal quality to Plextor. the basic reasoning behind everyone liking plextor, is because they have that extra feature, burnproof.