The CRA is fairly particular[0] about income from the sale of a property. They want to know, for example, how long it has been your primary residence and if it was rented before then, what was the appraised value. You will end up paying capital gains on the delta. So, if you've been renting out a property, move in to it for 6 months and then sell you'll be paying capital gains on everything but the last 6 months. The only time that works out is with a sudden spike in values.

[0] source: an accountant I know that wants to stay in good standing with the CRA :-)