up to you what you do, i took one of mine back and changed it for a 850, the other got a RMA as was faulty due to is keep disconnecting and as these are now end of life i got a 850 back instead.
how long have you had the SSD for? as terrier said there is a quick fix to restore speed if that is the issue for removing it but there is another fix due, did you run the performance tool and secure erase on their first fix of this issue as it did fix some of the drives but not all