I have two Superdrives. Since the upgrade to 10.11 (it might just coincide) they don't accept disks any more. I tried rebooting, sending eject commands to both drives etc.
They appear as "Unsupported" in drutil but look fine in "About This Mac" Storage.
$ drutil list Vendor Product Rev Bus SupportLevel 1 Apple SuperDrive 2.00 USB Unsupported 2 Apple SuperDrive 2.00 USB Unsupported
I tried running drutil against both with all sorts of parameters (getconfig, info etc.).
I also tried rebooting the Mac and disconnnecting it from power for a minute. (It's a Late 2013 iMac.)
Found this Apple support community thread: Superdrive not loading discs after upgrading to El Capitan
And I did try the drives with my AirBook (also El Capitan) as well with the same result.