Guy,
Sure, they do the same basic things - record, store and playback files. SATA has greater throughput and should give you greater recall speed of instrument samples. They would be a boon to anyone used to using FW drives for VSL.
The only thing faster would be a 2 Gigbit Fibre Channel PCI adapter card with Fibre Channel drives. However, the main reason not go that path is that the card and especially the drives are so espensive. Mainly it's the drives that are the problem because they are like slightly more expensive SCSI drives and have a serious size limitation. You would need several of them to hold VI alone.
So in my estimation external SATA is the way to go. My plan is to give the cabinets that hold four 500 GB drives and do a RAID 1 striping. With this method I can have VI and the rest of VSL and other samples on one pair and all these would be automatically mirrored (backed up) on the other pair. I recently had a LaCie Big Disk (500GB) go bad on me wih all my VSL and some of my other samples and it was an absolute nightmare for two weeks. I never want that to happen to me or anyone else again.
My specific references to the G5 were because I use one and from your previous postings I am under the impression that you have one also. What I said about G5's also goes for other computers - except for the new dual core, dual processor G5's since there are currently no manufacturers that I'm aware of that make PCIe cards for eSATA solutions.
Now, if you plan to go this path please be prepare to sacrifice a PCI slot for the adapter card. I have a Pro Tools HD Accel2 that uses up the two other available PCI slots so going this direction means that there will be no going back for me. So I intend to implement this solution after NAMM and I see what all is going on with VSL (MIR), Digidesign, Logic and audio interface manufacturers. But as of now I'm emotionally committed to this as the best way to go.
Best regards,
Jack