Not much help for a volt mode system though... at light load you have an un-damped output cap fed from an inductive source, this is always a problem for any volt mode system, so unless you add appropriate feed-forward at the volt sensing resistors, compensate the opto coupler, and other things related to the particular control IC, and use the minimum output C you can get away with, the response of your volt loop will have to be slow and damped if you want stable operation under DCM at light loads and high mains...
- - - Updated - - -
I note in app note 4137 above - they don't show any transient performance of the power supply, I can guess why...