Promise vTrak - Optimal number of LUNs in Xsan

Hopefully a simple question. I have a Promise vTrak E630fD 16 bay dual controller RAID that I'm configuring for use with Xsan in a uncompressed video serving environment. From research, it's my understanding that the optimal configuration (according to the Xsan documentation) for uncompressed video is 1 metadata LUN and 4 data LUNs. It's unclear whether this configuration is to be achieved using just a dual controller RAID or if it's supposed to be a RAID in conjunction with an expansion bay.

In other words, my question is would I achieve any performance benefit over my current scenario with two data LUNs on my RAID (each consisting of 6 drives in level 5) or four data LUNs (each consisting of 3 drives in level 5), both scenarios using one metadata LUN. I know four data LUNs is the optimal choice for video performance according to Xsan, but is there a performance increase with level 5 RAIDs when setting up multiple LUNs per controller? I know that I'll lose some additional storage space (2 x 2TB in this case) as well as reduce the likelihood of failure since I'm reducing the size of the level 5 array, but will I see any real performance increase from doing so? Thanks!