Especially the top-loaded sail cover. Ours has a zipper along the top also, but unlike the stacker our lazy jack lines go straight to the boom. This allows the sail cover to be rolled alongside the boom (fully retracted and out of the way) while under sail. Either way, it's much easier to deal with stowing the sail (it drops pretty neatly in place) and using the cover. You can see the cover rolled along the boom in this image.