Just as another datapoint, I finished my Kaiju a couple of weeks ago. I ordered during the last sale. There's zero transformer hum or vibration. One day I was chasing a 60Hz hum between channels, swapping tubes and changing outlets, but it was due to a cleaning pump that had been plugged into the house circuit.
I do have a low but noticeable hum at the speakers (Zu Soul Supreme which are 16 Ohm and 97dB/W sensitivity). I've ordered the DC supply which I anticipate will clean that up.
And by the way, it sounds fantastic and can push the Zu's to high volume very easily, much more powerful sounding the First Watt F3 that's been in the system lately which is rated as 10W into 16 ohms. The Kaiju has a jump factor that is almost shocking for a 300B SET amp but with that holographic presentation that I'm always looking for. It think the Kaiju also pushes deeper into the bass with more authority.