Running OS off RAIDed drive?
The only positive evidence I can find is one can install  Mac OS X server on a software RAID set. The instructions state that a standard Mac OS X needs to be installed before the Server software installation. The only drawback is that, among other things, a Recovery volume cannot be created and FileVault cannot be used.

One could interpolate that you can indeed install Mac OS X on a RAID, but some very important technologies will not be available.