There has been a lot of comment in the press over the last few days about problems with the latest firmware for 850 Pros - 2B6Q. The SSD we are testing is running with the previous version - 1B6Q - and has been extremely robust. We had been thinking of updating to the new firmware, and still intend to do so once we are a little further through this evaluation and the upgrade issues have been resolved. Since we have also recently purchased 850 Pro SSDs with the 2B6Q firmware factory-installed, we contacted with Samsung to clarify the situation. They have confirmed that the problems people have experienced have been with the update process itself, NOT the firmware. Samsung's response to our query was:
The firmware issued with this update were not caused by the firmware itself, but by the software solution. As you already have the newest firmware and it has been proven to function correctly and well, you can use the SSDs just as intended.
So if you have already updated successfully, or buy a new SSD which comes with the latest firmware, it sounds like you should not have any problems. We will keep you updated with how we get on.