I started another thread on the matter. But basically on Friday it started to feel "slow", like I was on a notebook hard drive. Later my automated WHS backup failed, which usually indicates a file system error, and when I went to use it again it was slow and I had a mail program complain about a corrupt file. Checked SMART statistics, everything was fine, so I scheduled a chkdsk.
Chkdsk ran - detected 8 "unreadable file record segments". It finished stage 1 of 3, then rebooted, and did it all again. This time there were 32 bad segments, and a ton of other errors. This time Windows didn't start. Rebooted into Startup Repair, wouldn't get out of it even if I tried to force Normal or Safe mode. So I let that run for 4 hours (it says it may take an hour), gave up, tried a bunch of other things to get into Windows - nothing.
So I put it into another system - it wanted to run chkdsk on the drive but I skipped it - however the system then saw the drive as "RAW" file format and corrupt. Did a bunch of tests, SSD Toolbox read/data verification tests failed, so I tried another chkdsk and this time there were 40 bad segments and pretty much every single file on the drive reported an error of some sort (I'm talking an hour of quickly scrolling text of errors). So I wiped the partitions - worked - used SSD Toolbox to secure erase - worked - and tried to recreate a partition - failed. Right now all I can do is see the drive and access SMART/info properties. Any attempt to create a partition just hangs with the HDD LED on (rest of the system works, but the SSD hangs - if I try to read SMART it takes over 60 seconds to get a response).
Only interesting SMART statistic was 74 reallocated sectors, but that never grew during this (although I will say I could have sworn it said 73 before my first chkdsk, but I could have been wrong).