i have been trying to find consensus on this point also. I believe its not a case of one size fits all for enabling TRIM on SSDs for OS X. OWC who have their own brand of SSDs specifically targettied for Mac users officially discourages the enabling of TRIM on OS X when using their brand of drives. This because the Sandforce controller that they use has its own garbage collection routines that negates the need for TRIM on the OS.
I would like SanDisk to confirm if the controller in the Extreme supports background garbage collection. Because I am reluctant to make any unsupported mods to the OS unless I am very confident that there is clear evidence that its required. If there is BGC on these drives I wont be enabling TRIM on the OS, just as OWC recommends with their drives.
