Well crap, I didn't research the external enclosures good enough and they won't take my drives, only handles 2TB total. That would have been handy to have in the amazon product description.
Read some colorful reviews of the drobos, shan't be doing that. Huge price on those things too.
Given I can't really find a good way to easily back up my big drive to many small ones I guess I should put some sort of RAID together for the backup disk.
Now I am thinking about doing a different motherboard so i can have more than one PCIE slot, add a PERC 6e and find some sort of SATA external enclosure that can accept between 5 and 8 drives that works with the PERC 6e. Not sure how it would handle not having the backup drives off, I suspect not well and it would interrupt boot?
Alternately I could build a second Machine to do backups, don't really want to but it might be the best way.