Repeat after me: "RAID is not for backup." It is designed for uptime, speed and/or space depending on the version. You don't want your critical backups being reliant on two things: the controller card and software functioning properly, and hard drive failure. The fewer points of failure there are in the system, the more likely it is to function well.
I go the KISS way: three external HDDs. I have two Hyperdrive SPACEs which I fill with the backups. And I have a 1TB external HDD which I store at work for offsite storage, in case of fire or theft at my home. I fully verify the entire backup every time I run the program. And I don't use any proprietary archiving methods, but plain CR2 files. I never ever delete anything from the backup drives to avoid user error, and I don't keep them plugged in the computer to minimize the same.
Offsite is something which many people seem to forget. Theft, fire, flood, leaking pipes, etc. has destroyed numerous people's pictures. A colleague lost the entire collection of childhood photos of his daughter that way. I'm thinking of getting a fireproof safe, but that's mainly for paperwork, and doesn't protect from theft.
The main thing I'm worried about with this setup is viruses.