Vigier Guitars

I've read somewhere on the Basschat.co.uk forum that the neck design of the Passion basses underwent a change at some point: from an almost flat, zero relief neck to a neck with a "textbook" amount of relief, because most bass players prefer a neck with a little bit of relief or curvature in it.
Is this correct? Can somebody confirm this information?
And does anybody know when this transition from almost zero relief to some amount of relief was implemented?