Switched out my 250GB for a 2TB WD EARS yesterday, reset to factory defaults, installed 1.10b05, formatted the new 2TB drive, left the other drive intact with data (no format).
Drivewsie, everything working perfectly. I have copied about 200GB of data onto the new 2TB drive, it all copied on at the maximum speed my network allows, so no sign of any performance issue with the 2TB.
Very happy, now just waiting for 1.10b06 to come out, as I suspect 06 is set to become the official 1.10 release a little later this month.
A little suspicious about the fan not appearing to run, having said that the device has not not been all that hot. Also I seem to recall people complaining about the fan running too much. Have D-Link said anything about changes in 1.10 to the how the fan is controlled?