Re: Rebuild times?
Samsung 960 Pro can write roughly 2GB/s, so a 128TB drive would take roughly 18 hours to fill, so that's the theoretical minimum. Array usage during rebuilt etc. will of course be a factor.
This is in the same realm as rebuilding hard drive arrays with 10-12TB drives. (assuming a very generous constant 200MB/s write speed)
The M.2 PCIe3.0 x4 is limited to about 4GB/s, so there's still pleanty of headroom for Samsung to develop a faster controller.