I knew the 160GB and larger versions had parity, kind of figured it was dropped from the smaller sizes for $$$$ reasons. I never knew this about the smaller 320s, very interesting. Went and read more on the 320, seems the parity was introduced to make up for 25nm deficiencies (inline with what SandForce/vendors did when going to 25nm, just doing the opposite of taking away usable space and calling it the same size on the label).

Frankly, I would prefer to calculate WA based on total onboard NAND regardless of its designed usage (WA inflated from parity doesn't seem so bad as long as it's explained...after all, for every 1 byte sent, ~1.2 bytes do get written). But we don't know exactly how much parity data is being written so I won't (not sure it's a safe assumption that the full 8GiB of the sixth die is used for parity). I'll continue backwards calculating WA using wear indicators multiplied by total non-parity NAND (not that WA is fluctuating for any of the drives). And with the Sandforces, no need to backwards calculate WA because of SMART 233.

As for normalized writes, it's probably easiest to base it on IDEMA capacity. This means everything, relative to the other drives, is unchanged except the 40GB V2, which I had based on 48GiB and will now base on 40GB. This means 55GB for the '60GB' 25nm SF-1200 drive (not sure what SF-2200 has for capacity of their 25nm 60GB SSDs). (aside, I realize normalized writes don't quite work if OP proportions varies within a product line, sigh)

Out of curiosity, how much NAND do the 80GB and 120GB 320s have?

With the new (to me) knowledge that the 320 40GB has a parity scheme...I don't see the 320 40GB dying for quite awhile.