Really depends on if you can afford it or not. If you can, then it's worth it, there's another thread going on right now about the pro's of SSD. But if you even think you can't afford it stick with the Raid 0, you'll live w/o the SSD!
FWIW I've got almost all of my set ups with a SSD, then RAID 1 for pictures, docs etc. and then either another HDD for back up or an external and it seems to work great for me. I've also set up one rig that uses Raid 0 and another larger drive for the back up and works great (not as great as the SSD) as well. So really, if your comfortable putting down the money, then do it. IF your even slightly uncomfortable, get the HDD, and save up until your more comfortable with the SSD cost.