The question is, does it's in production ?
If yes, re-activate the hardware maintenance. For DELL a SAN in production must be in maintenance. As they will be able to update the drive firmware too if under maintenance. If DELL got stock those disks stock and you dont want to re-activate the maintenance I suggest you to stock some, as DELL keep the warranty/store stock separated. I will repeat my first statement, for a SAN in production for DELL it must be under maintenance.
If no: You can put any drive you want in the SAN. You might have to buy a full array of them on the other side as your array might don't want to use the drive alone. (I did it in a PS4100 for a lab, got 24 normal seagate SAS drive and the SAN seen them.)
The why:
An example I know: Their firmware allow the SAN to snapshot a disk that is near failling to another disk, to prevent a long recover time. So, you scrap the SAN resiliancy special feature by using non dell firmware.