For info:
I was going away for the weekend, so set the X30 to back up to an external 2Tb drive at 12:30am Friday morning (or late Thursday night if you like). Went away Friday afternoon, the X30 was ticking over as last time I did a back up - so expected approx. 6 days to finish - so about midnight next Wednesday.
Came home at 12:00 pm this afternoon and it was backed up, successfully! So 2.5 days max, possibly sooner!
Bought the 'green' WD 3Tb drive as above, arrived today too. Took the 'old' 2Tb HDD out form the X30 - guess what, it was the exact same model, just 2 Tb, so happy with my choice as I'd no problem with the old one.
Put the drive in, did a format (in Linux) and set it to restore from the external back up. Let's see how long it takes (from 4pm today)?

PS
24 hours later, its backed up the playlists, favourites etc - and 25,000 tracks (mainly wav and flac) - so I estimate it'll have finished by 8pm tomorrow night (~52 hours to restore 54,500 tracks). Happy enough with that. So in all - it appears the last firmware may well have included something to speed this up (on the X30 anyway).
