I am ignorant of these specific surfaces in this particular paper, but...having said that:
First: I highly doubt that the thickness quality of the matte would be manufactured to be inferior to that of the lustre. Are you, perhaps, seeing that the luster surface has a bit more 'tooth' and, thereby, come to the conclusion that it is 'thicker'?
Second: my personal choice for ALL paper, B&W or color, is matte. In the real world that hardly ever works out because I buy much used stuff and one has to take what one gets in the deal. But there is a certain richness of the matte surface that I find to have what I would call aesthetic depth. I know that the reflectance scale is less than that of the glossy but matte is NEVER difficult to look at (no reflections) and, at least to me, it imparts a solid neutrality that is satisfying. In B&W it reminds me of a charcoal drawing.
bvy: hold a 100 sheet box of each in different hands. You will soon tell whether one is thicker than the other. - David Lyga