What actually changes when you downsize out of Nutana is the sale itself, not a tax exemption. Nutana's character homes from the early 1900s often carry higher land value than newer areas because of the neighbourhood's location on the river, and that land value is exactly what a bare assessment number tends to miss.
Selling costs run the same regardless of neighbourhood: seller closing costs of 4 to 6 percent covering commission, legal fees and adjustments, plus legal fees typically $800 to $1,500 on top for the purchase side if you are buying again. None of that changes based on which Saskatoon neighbourhood you are leaving.
A hand-reviewed look at your specific Nutana property, including any renovations public records missed, will tell you far more about your actual proceeds than any exemption search would. Get your hand-reviewed valuation from Joel Dyck.