as a heavy weight cat sailor I can confirm , extra weight aint good , lightweights with umpteen million to one downhauls , modern cut sails and rigs can hang in upwind and then dissapear offwind , any minor advantage of weight upwind is more than offset by the MAJOR disadvantage offwind .
Heavyweights can win , but you have to sail a flawless race , hit every shift up and down ,catch every gust , boat handling spot on and rely on the lightweights making a mistake , at top level this aint going to happen , but possible at club and area racing

or curiously in drifters I've never found weight a handicap at all.