As for the NAND, interested to know what the write-capacity of those cells are... With each feature size drop and the increase in bits stored per cell has seen a drop in the number of writes per cell... But who cares if you can only write to your 8TB SSD 1000x (or even less) times over? You've got a 8TB SSD! (note: sarcasm mode is on).
Honestly, four bits per cell scares me. Three bits was bad enough in that you had to distinguish between 8 voltage levels. Now we'll have 16. I'm more concerned with how long the cells will hold data than with the number of writes. With wear leveling it's pretty much impossible for most people to wear out a large drive, even if the maximum writes per cell is only 100. On the other hand, if the drive sits on a shelf will the data disappear in a matter of months, even weeks? Really, I expect unpowered drives to hold their data for at least two or three decades. The rationale here is if you didn't look at the data in that long, it's probably worthless to you but you might want to retrieve data which has been sitting for a few years, or even a decade.
With each increase in bits per cell the incremental drive capacity increase is less but the chances of losing data probably increase exponentially.
