I doubt that you will need an ssd raid option. The single ssd you are looking at will speed things up nicely.
Keep your working files for Photoshop on the SSD if you have space copy them to the raid when you are finished. It's the closest thing to keeping your whole project in RAM.
I think the important thing is to run good backups. You don't need to worry much about a drive dying if everything is backed up like it should be.