I suppose I can understand putting laminate underlay under the vinyl to make it softer, although you would not do this in normal circumstances as it would be too soft causing the vinyl to stretch and move. I am confused though why put a breathable membrane down. The floor is sealed underneath with shultz/tettraseal and you are putting down vinyl which will seal the top. There is no need for it.
I feel there is every need for it
when you remove your carpet from a dandy you will notice that the floor is pop riveted and these will cut into the vinyl
you will also notice that the floor is not made of a smooth timber and it has some roughness to it
but hey if you like to read braille with your feet just put the vinyl down on its own