How old are your Extreme SSDs, or in detail how long are they in use and in what environment (server 24/7, desktop, notebook)?
As SanDisk grants a three year warrenty and I have scheduled a weekly full backup of my system including a backup of my documents every two days I think I will risk to use the SSD some weeks until more details are known about the sounds it makes.
BTW: I installed firmware R201 right before installing my system. But that did not change anything on the sound it makes.