Oh, well... although I said that I'll wait some more time until I upgrade the firmware of my Seagate Barracuda ES.2 ST31000340NS drives, I did it today!
=== START OF INFORMATION SECTION ===
Device Model: ST31000340NS
Serial Number: 9QJ2VT98
Firmware Version: SN06
User Capacity: 1,000,204,886,016 bytes
And well, it still works.
/me happy :-)