If they actually start a business, live here, and pay taxes on local and overseas income, certainly some good occurs.  If they use shell games to merely buy property with the "investment" funds, hide income, and use Canada as a spare room, then the benefits are limited and negatives very real (empty houses, prices gone nuts, influence bought from Christy and Justin...).   As dual citizens they don't have to be here much.  So scrap that and see who chooses to be Canadian and only Canadian...