When trying to detach an eSATA disk using udisks I get the following error message:
udisks --detach /dev/sdc
Detach failed: Device is not detachable
Unfortunately there's no way of easily figuring out if a disk is connected via eSATA or not. And if you examine 'udisks --dump' it will most likely say SATA, not eSATA. There's a bug filed upstream about this, check the upstream bug tracker. So closing as UPSTREAM.