I was bulk ripping CDs a few months ago and was running multiple SCSI drives to increase my throughput. The current Linux SCSI drivers will lock up the bus when you insert a disc and ruin any transfers already in progress on another drive. You'd think something like that would have been resolved at this point.
An actual SCSI device? And you're complaining about "by now". How old of hardware are you using? "By now" fixes are included in modern hardware on USB.
I have a number of Plextor CD-ROM drives that are more desirable than DVD-ROM for CD audio extraction. I have one USB Plextor but they command a high resale price. The point is that basic bus management should be sorted out and it clearly isn't.
A lot of CDs aren't in perfect condition, either because of scratches or things like https://en.m.wikipedia.org/wiki/Compact_disc_bronzing. When faced with damaged data, the quality of the drive and its firmware will influence whether the data stream corresponds to the original content or not.
