Vacancy is the number to model carefully rather than the repair budget. A newer building needs less immediate maintenance, but if the second unit sits empty for an extra month or two while you find the right tenant, that lost rent can outweigh the maintenance savings for the whole year.
Legal status still decides how much of the rent a lender will count, the same as anywhere else: a permitted second unit under the City of Saskatoon's rules supports financing, and the Residential Tenancies Act, 2006 governs whatever lease is already in place if you are buying with a tenant attached.
Run the actual numbers for the specific property rather than assuming newer construction automatically means better cash flow. Get your hand-reviewed valuation from Joel Dyck.