I spent 2 months with Massi and Celso (& Colby) while doing 2 electives at McGill (MGH/JGH) and it was a great time. Their place is very nice and clean and the location is simply great: both near to the plateau and quartier des spectacles, you can easily explore Montreal from their place.
They are good welcoming hosts and Colby is a super nice dog that everybody has to like.
Therefore, a highly recommendable place to stay in Montreal!