Regardless what you SHOULD read in the marketing material - and I will not go into doing your homework here - be aware of the following:
- Storage Spaces under RAID setup are supposedly SLOW.
- Storage Space Expansion with additional discs is problematic (no rebalancing)
Check http://blog.insanegenius.com/2012/09/22/storage-spaces-leaves-me-empty/ for a good discusssion also with core arguments - I am on the same line as he is. Nice v1, now please fix the issues and I will use them.
There are some advantages, but if you dig into it they are really perfect for archival but have some limitations for anything else, at least in v1.
The last sentence says it all: "Until Storage Spaces gets thoroughly documented and improves performance, I’m sticking with hardware RAID solutions".
At the end you have to give it a try - imho what you should have anyway is a raid controller in the middle that can cache to SSD (i.e. transparently map reads and writes to the discs to ssd) such as the new Adaptec line (which also can run in a "Map the discs through to the OS without raiding but still use a SSD pool for caching mode) to bypass the performance eimplications.