Over provisioning might be more necessary just for keeping performance consistent over time. 20 to 28 percent is somewhat normal for an enterprise drive, so that will give you more endurance and better steady state performance to boot. The 512GB would really be a 480GB as the Crucial uses about 7% spare area. So really anything below that as additional area would just be gravy. I can't really say what kind of performance degradation happens to 8 drives together over time, but I imagine over the course of a year it could get pretty messy, and just going to 14% percent OP could stop quite a bit of it from happening. That's not my department though, perhaps CT could elaborate.

The whole OP issue is pretty interesting, and that's why I wanted to try a second endurance testing drive set up OPed. I believe much of the additional TBW rating of the new 710 drives is due to the heavy OP, so it stands to reason that if I were to get a 470 and added some extra OP that I might be able to add 50 percent to the lifetime.