I would go with the SSD, but that's because I have one and man does it wang. I hit 143dbs with 1 15" SSD in my car. For that loud, and the price that it is, it makes baby jesus cry.
No one really knows about the RDs give it a month or so for some reviews then compare thats what I would do. The Fi SSD is proven Im not saying Fi is better than RD. Im saying RD is to new to compare at the moment. my opinion