The Voith tugs were chosen for La Baie because of their superior control (at the time ASD tugs were very rare and not proven) Alcan looked at the navy tugs in Halifax and other V-S tugs and because Georgetown Shipyard (now East Isle) had built all their tugs and had built the navy tugs it was a good fit.
I hear Alexis-Simard has been bought by Groupe Ocean for use in Ontario, to replace Escorte, a smaller V-S.