That thing has a few problems, and they are related.
Firstly: The enormous inrush current, best part of 100A in a 100W supply?
From this stems most of the other difficulties, thermistors while not perfect, are reasonably effective for this, or do the opto triac, mosfet or relay soft start thing.
Secondly (And this is problematic mostly because of that 100A inrush), you have the ringing in the common mode chokes, easily cured just place a 50 ohm resistor in parallel with each winding to kill the Q (Experiment with values, but fix the inrush first), given the very low impedance of the mains you should still get sufficient HF attenuation.
I would note that the excessive inrush current is probably a far more serious reliability issue then the momentary overvoltage on the main cap.
Regards, Dan.