On Fri, 8 Feb 2013, Adam Goryachev wrote:

Though, like I said, would adding an extra SSD to the RAID5, and 
reducing the size of all partitions by 20%, and then doing TRIM on that 
newly freed space, would that improve performance because of the extra 
free space the SSD can "work with" ?

Yes, that probably doubles the overprovisioning on the drive, which should 
be beneficial in a lot of aspects.

<http://en.wikipedia.org/wiki/Garbage_collection_(SSD)#Over-provisioning>

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se