Peter -
There are advantages to each product IMO, and you are right on with both of your questions. BF over Z does give a deeper look and Zaino over Blackfire does add that crazzzy zzzany shine. The Z shine makes it hard to photograph.
The color change you see in the pictures is in large part due to the lighting condition - its one of the things I like about the Agean Blue Pearl, BUT it is also due to the difference in reflectivity, optical clarity and perhaps thickness of the protectant. I will try to get a picture under similar lighting conditions if the weather cooperates.
I "think" the Z is extremely thin, and the BF only very very thin (i.e. several times as thick as the Z.) I did get a deeper look with several layers of Z5, but nothing as dramatic as the BF.