Damn, copying files from network over USB via regular (non-mass storage) mode stil f'n freezes up within a minute... PoS.
PS: aaaand mass-storage mode does not even work, it's unreadable by Win8.1 - arrgh...
So essentially in 20 minutes I was only able to copy few mp3s onto the Z30, then it frozed then nothing else worked again. Awesome. Truly enterprise (PoS).