Lots of variables
I can speak from personal experience only.
Setup:
Areca 1882ix
Eight Crucial M960 SSD drives in RAID 1+0 (4TB storage total, 4TB redundant)
Two logical volumes, 2TB each
There are two logical volumes of 2TB each because OSX would never let me boot from anything larger than 2TB.
I am in the latest build of Yosemite, and the SSDs are rock solid and super fast. They will boot from either 2TB volume.
MacPro 3,1