There are a lot of factors involved in RAID, and firewire raid in particular. What is right for you depends wildly on what, exactly, your needs are, but here are a few thoughts I've come up with in shopping for dual FW cases:
1. Serial ATA: Not yet. I don't think I've seen any SATA FW cases, and I don't know why you'd really care anyway--there's no significant speed difference at this point, and SATA drives are more expensive. The FW bus would be the limiting factor in either case, anyway.
2. As the previous poster said, two individual cases will work just as well as a dual-drive case, with the added bonuses that you can put each on a different FW bus to increase speed, and you can use/sell each seperately if you want.
Two seperate FW enclosures with a software RAID setup (OSX has RAID built in, so I'd just use that) is probably the cheapest way to go as well; the only dual-drive case I've seen that was cheaper than two seperate cases was from computergeeks.com. I bought one, for about $70, but it's very industrial, is only FW400, and has no built-in RAID featuers. I'm trying to sell it now, since I decided I preferred to use seperate cases.
3. That said, since you want to do RAID 1, I'd personally get a hardware RAID case like the
Vanguard III from FirewireDirect. I much prefer hardware RAID to software, since it doesn't rely on any specific OS or software installation, and if you're willing to spend the cash for the enclosure, it'll be completely plug-and play with no worries about your computer recognizing the software RAID format, etc. All around the safest, smoothest, and slickest way to go, but it's also the most expensive.
Good luck.
