if your changing from single crown to dual crown it's always best to check with manufacturer 1st for where you stand on warranty, many frames will have the warranty voided by doing this idk about the norco tho', a phone call only takes 2mins, agreed on why you would bother tho', can't imagine it would ride too well altering the geo that much.
i can realate to him as i love good singles but feel much safer and prefer tripples on anybikes always had tripples and alwayse will lol inless i build a jump bike