Are we talking about a lot of money difference between silver and gold for this particular mouthpiece? Gold feels better on the lips in my humble opinion. If your son only plays one mouthpiece, why not get it for him? However, I would caution him that if the mouthpiece is lost again, it is his money that buys a next one. He ought not to expect you to cover the cost again. It's his responsibility! Could be the gold mouthpiece will be taken care of better, who knows?