Wow, 4x the life span. Now I wouldn't even know where to start guessing of when the M4 will start failing. 850-900GB sounds good for a start, maybe 1PB!

Good Luck with the other drives there BAT. G1 drive will probably suffer what I had with my G2's not being able to trim properly in Raid. That SLC drive though, hope you got a PC that will be running for the next few years to test that one