FYI : Visa stamp on old passport still valid if it is not expired on old passport. passport holder have to carry Old and New passport to travel.According to my understanding if you have a new passport then consulate will invalidate the old passport which mean everything related to old passport is invalid including travels and visas because Visas are one to one documents means that they are only valid to the document they are issued to (I do not have knowledge if there is exception to this). I do not suggest to get into passport change unless absolutely important. Remember any change in travel document still needs to be submitted to CIC for PGP which means one more step towards your application.