Hi ninjapants,
If you feel that you are bottlenecked by the hard disk when it comes to playing games, carry on with the RAID0 config. But such performance comes at the expense of stability. One crash can corrupt all your data. Hence, it might make sense to have 2 separate drives, but not in RAID 0, and if that is your choice, I'd recommend the 850 EVO, since it has SLIGHTLY higher performance but significantly longer life.
Cheers.