Well, other than the fact that you didn’t really answer Bill’s question #4, there’s not much else anyone else can tell you.
It appears anyone buying an actual 3TB external drive, whether from WD or from Seagate, has had no issues under the patched firmware.
That’d seem to indicate that the Live/Live Plus firmware is capable of working properly with USB drives greater than 2TB.
Now, if it doesn’t play nicely when a 3TB internal drive is placed in some enclosures, that tends to point to the enclosures themselves, since the SATA drives are basically identical to the ones inside the extrernal drives known to work.
It still seems likely that the enclosures have loaded a driver on the PC, in order to bridge from the GPT SATA drive to the PC itself.
It can still be WD’s bug, as well. I’m certainly not holding WD faultless and blameless. But it sure seems more like it’s the enclosures and they need drivers to work over USB with large drives.
What happens if you attach one to a printer’s USB port? Will it recognize the drive, like the PC does, or will it refuse to see it, like the WDTV?