In defense of the heavier egg. Many moves I use require that the egg is thrown, tossed or squirted from one corner to another. This goes from chancy to impossible with a real, blown egg, or one that is very light. Like balls for cups it is helpful to have them with at least a tiny bit of heft to them. If a spectator ever commented on the weight I am ready to tell them that it has three yolks but so far no one ever has.