I just picked one of these up. Horrible ground noise.
Now, I'm assuming it's probably my guitar, but I thought I should check before I open up the guitar and start resoldering all of the connections and checking grounds.
1) The noise goes away -- other than usual single coil hum which I am familiar with, and this is not the same type of noise -- if I touch the bridge or, especially, jack socket. It drops a little but doesn't go away completely if I just touch the strings.
2) Moving to a different mains point, and ensuring no other devices are connected or on nearby makes no difference.
3) I don't really have this noise issue with my THR10.