Mine went in the shop yesterday for the clunk (4th time a charm?) and the FOD informed me that his FSE advised that they check the motor and transmission mounts. According to him they haven't broken or shown signs of severe fatigue but that they appear to be a bit "soft" so they are replacing them.
They assured me that this was the cause of my clunk. It should be back in my possession tonight and I'll let everyone know if this fixes the problem after a good slow drive over speed bumps. Fingers Crossed.