About the controller; I have run into on-board RAID problems with major manufacturers recently. I suspect that in the increasing pressure to cut costs, the software is less robust. In contrast, there are good third party RAID cards using PCI-e sockets that you could use for the SSD array. That would probably mean internally cabling them, but since they are the boot drives, that isn't the end of the world.
One of the tricks that we have found with third party brackets is you can break out your trusty drill, and open-up/widen the bracket slots/holes until you get a fit. We then use some of those vibration dampening washers that come with 2.5 spindle drives to snug up the SSD once we get it where it needs to go. Although, cardboard does give you certain DIY cred all it's own.
