I could not find any 2½" portables from Seagate or WD on their websites with eSATA interfaces. You MIGHT find one with USB3 for speed comparable to eSATA, IF your portable computer has a USB3 port. But does it have an eSATA port? I'm wondering why you want a portable HDD with eSATA interface in the 2½" size.
Because I should copy 100k files back and forth.