I can certainly see where you guy's are coming from, but at the same time something doesn't quite add up.
I flashed all three of my MP600's (1x1TB + 2x2TB) after having read this form post and took the risk anyway.
Result: All three drives flashed well and performance seems to be OK according to AS SSD.
A few notes:
(A) after flashing the firmware and re-booting I saw less than ideal write speeds like many of you. After a second reboot and allowing the system time to settle I saw good performance restored.
(B) allowing the system and drives time to settle after booting into Windows seems to have a notable affect on AS SSD Benchmark results. Jump the gun and you'll see off-kilter results.
© not really a caveat... Even when I was initially seeing lower than normal benchmark scores it didn't make since because if anything since flashing to firmware 13 my PC has felt a little more in tune - like it's running a little smoother, a little snappier. PC performance vs benchmark results were definitely at odds - at first.
AS SSD Results: