The extra 8lbs from middleweight to super middleweight is a significant jump. Look what happened to the middleweights who fought in the super 6. Arthur Abraham was seen as a top fighter before mixing it with Dirrell and Froch, all his vaunted power at middleweight disappeared when faced by a true super middleweight. Golovkin at the moment is still unproven against genuine top level opposition, I suspect he may come undone when faced against a fighter who can actually box and move. Any fight at this point would have Froch as a big favourite.
GGG would destroy Froch. Golovkin's ring IQ is off the charts, while his technical ability and I believe even his power surpass Froch's by some distance. Sorry, but Golovkin vs Ward would be a much more equal comparison.