Sorry to hear you guys are having problems. Take this with a grain of salt, as we do not seem to be having the cyl head issue here in the USofA with our lower sustained speeds.
From what I understand it is an interference issue, the cyl head, cyl head bolts, and hollow locating dowel tolerences are either incorrectly designed and/or manufactured so that the torque is is not enough to properly compress the head gasket. The fix seems to be some new parts and a higher torque value. (I have not read the KTM documentation on this myself, just gotten second hand info.) Cheers, Mack