Hi to all,
for what it can help the "post-fix" discussion here, my two EVO drives for which I started this thread, are running fine and at maximum speed since the firmware upgrade. I'm using them in the same PC as before and they are on 24/7 as before, too.
Looking at "fixed" drives that degrade like without fix, the only thing I can think of is trying to restore again the drive speed with DiskFresh and wait again for a couple of months to see if this changes something.
If it is true that in the new firmware Samsung changed the cell reading algorithm, maybe a "reset" made to all cells like DiskFresh does, can recalibrate something which didn't during the update... Just my 2 cents!
EDIT: ah and if after a DiskFresh pass the drive is still slow, then it may have defective cells...