@amigadave
correct me if I am wrong, the speed at which the data can be processed and burned to the disc certainly is dependent on the speed of the CPU. If it were not, then a SCSI CDRW connected to my A500 w/7mHz 68000 could write CDs just as fast as my A4000 w/50mHz 68060.
68000 A500 with SCSI CDRW connected is able to burn CDs just fine, if you burn from image file and the source HDD and the SCSI interface is fast enough.
The burning process only gets CPU bound if the CD is burnt on the fly, without image file.