I do have an SSD but i never put it in a RAID setup.
I have my OS on the SSD which greatly improves boot up and lowers noise level. Then I set one of my 1tb drives for all programs. I do see an increase in load times.
However, in World at War, I found that particular game made no improvement. Something about the map data access on an SSD as opposed to conventional.
When using Cat10.4, the SSD made no difference. I still had long load times. In the end, if you go with an SSD, you may see improvement but the only way to know for sure is to try.