Weight has **** all to do with it,
Oh but it does, you see to change direction (up and down) over the bumps takes a LOT more energy and impact when you're twice the weight of someone else. I notice a difference in smooth-ness of my own riding +- 2 stone, despite my skillz not having changed much in that time.
Without having invested any time in envelope calcs, I'd guestimate that a light person is better on a hardtail (lighter to bounce over stuff and flick about over good lines) and a heavy person is better on a full sus (able to utilise the long travel and momentum to "make" lines, with tougher kit that withstands the impacts)
Well, thanks for your insight, pity it's total bollox..
think you've possibly confused the difference between the performance of a heavy rider and an overweight, weak rider!!
and as for your full sus arguement, simply take a look at that little Sam Hill guy destroying the entire field by making lines others can't on the roughest techiests DH tracks in the world.