I used fill light when I had my own wedding photgraphy business.
I only used fill when it was a last resort so not to burn out the dress but on occaisions it was required.
I would manually set the flash to maybe 1/4 or 1/2 of the camera exposure settings.The use of a white reflector works well as it is not so severe as flash or can be used in conjunction with flash.
Have to say your shot is very very impressive.
Maybe rather than copy david Hill you should now develop your own style..you ave a pretty good base to start from.
Eddie