With Hockey pucks coming in at a heavty 6 ounces, a lacrosse ball at 5 ounces is a superior choice.
I have used a rubber hardball for years. It has sat in the bottom of my tall drink holder on my bag for ever. Even doubles as a beer can spacer in the drink pocket...making it far more accessible.
I just seem to be able to throw a hardball more accurately than a hockey puck. I do not know the weight though. I think it is lighter than a lacrosse ball, which may mean you can throw it further and harder, but it is less effective in knocking a stubborn disc loose.