John I suspect that there is something about the paper which suggests in some people's "minds" that the paper is thinner as I think I recall seeing such a comment on Photrio but quite what it is I have no idea and I have yet to get any MGV paper to see if I will suffer from the same perception.
I should add that I use the word "mind" to indicate perception and not to imply that they are going mad or have weak minds
Mike