Hallo Terry and Mahmood,

with transformer solution leakage current is no longer a problem!
The trick is, that there does not exist a source providing 1200V. Only galvanically isolated sources of 300V. With symmetrizing resistors, there exists a source of 1200V, where the voltage drop across each capacitor distributes according to leakge current of each individual capacitor (Ris1 to Ris4). Then, of course, there can be an overvoltage at some capacitor.

But with transformer solution such a 1200V source does not exist! And there will no distribution of voltage drops according to leakage current.
Think just about how this leakage current should have to flow. With symmetrizing resistors leakage current comes from +V of 1200V source, flows through all capacitors and returns to 0V of 1200V source. But with transformer solution, such flow is impossible! If leakage current is flowing through a capacitor it can not charge up another capacitor sitting above or below him. Because then, the current must somehow flow back to him. But there's no return!!Leakage current should have to flow through the load against the direction of normal current flow, means from 0V to +V of sum of high voltage, but this is just impossible.
So, each individual leakage current does only affect the individual capacitor! The only cause is the discharge of this individual capacitor.

Kai