I must admit that in my experience the Blue Zulu has been more effective. I have also found that a turquoise blue hackle has been more productive than the brighter blue hackles.
I haven't tied any for a while but usually tie as a standard zula with black body hackle and just add a couple of turns of blue in front - the older and more battered the fly the better.
Exactly my experience, I have a light turquoise blue hen cape (somewhere...) which I use for my blue zulus, which typically I tie 'thin'.
