As I understand it Intel SSDs will use any left over space as over-provisioning on their own. Just create a partition that is smaller than the max and the SSD will use any space left over as spare area.
Basically, any unutilized space will just be more blocks for wear-leveling and to help ensure there are clean blocks when needed.
I'm curious of how it went. Did you get it working? I'm planning on putting three 320's in a RAID 5 on a Poweredge server myself, but have found very little information abou it.
Yes, our RAID 10 performs as expected. I'm not able to prove that the unused space is in fact being used as desired by the drives... but it seems to be.