|The only time you save when you're burning one disk when you have two or more optical drives vs. one combo DVD burner drive is the time it takes for you to respond to the message to eject the disk that was read, eject the disk, and insert the blank disk. |
There is no advantage regarding a DVD burner optical drive being SATA v.s. IDE, except convenience, if you have spare SATA data headers and not enough places to connect IDE drives. The max burst data transfer rate of optical drives is 66 mbytes/sec for drives capable of burning DVD-R or DVD+R disks at 16X or faster - that's limited by the max speed data can be read from the disk and the max speed an optical disk can be spun at without risking it flying apart - that's not going to change unless someone comes up with disks that can safely be spun faster, and/or disks that have a much greater data storage capacity than current DVD disks.
"Copying on the fly is even less reliable when both drives are on the same IDE cable because only one drive has access to the IDE channel at a time."
Have you ever actually compared the time it takes to burn the same data using the same settings in the burning program, or the time it takes for you to transfer the same large amount of the same data from one IDE hard drive to another, for two IDE drives connected to different IDE headers vs them connected to the same one ? Some others who have regularly answered here have, and have found there's no significant difference, with mboards that have main chipsets first released since about the mid 90's.
The data has to go from one drive at a time to either the ram (direct memory access mode) or to the cpu and the ram, then to the other drive from there - it doesn't go directly from drive to drive.
For mboards that have main chipsets first released since about the mid 90's, each of the two IDE drives connected to the same data cable has the same max data transfer rate per drive as ones connected by themselves on a data cable.