Yeah, I'd go with RAID1, I had a very old raid 0 setup on my dad's computers once; what wound up happening is I actually lost a few files on the drive where my OS was installed and those turned out to be something to do with the OS, I think the csrss.exe couldn't initiate at first and then later I think something happened to the winlogon.exe as well. Needless to say, I needed to do a new install of xp and it was not a fun experience. Honestly, you won't be able to tell too much difference between the two, and the chances of this happening are extremely slim, but you never know. Of course, you could just ensure your partition is not on one of the drives you use in the raid Good luck and hope this helped out.
Speed is a relative term. A Caviar Black drive on normal wont make you lag in recording. Your other system parts may. RAID0 just is a bit prone to crashing. Now you decide you want to lose 2TB or whatever the size is worth of data or speed the occasional 1 second lag while recording.
Just to add a point here. The western digital Black drives are not suitable for RAID configs, because WD disabled the TLER in them. I am guessing you have this model Western Digital Caviar Black WD1002FAEX.