The problem is that that's a lot of data to lose should something go horribly wrong.

I certainly hope if all this pr0n^H^H^H^Hdata is important to you, you have a more permanent backup?

In all seriousness, "something horrible" means two drives failing at the same time.. Short of your entire PC bursting into flames, that seems highly unlikely. The really, really, really important subset of that data should be put on CD/DVD and stored in a safe. The rest is probably very safe in a RAID5 array, assuming your RAID card/drivers/etc. are up to snuff.