An excellent example of the disenfranchisement that can be caused by using single winner districts to elect members to a legislature can be seen in the 1926 Canadian federal election for the province of Manitoba.
The province of Manitoba was entitled to 17 seats. The Conservative party had 42.2% of the popular vote within Manitoba but was unable to win any of the single winner districts.
Here is the data care of RangeVoting.org :
| Political party | % votes | Number of seats | % seats |
|---|---|---|---|
| Conservative | 42.2% | 0 | 0% |
| Liberal-Progressive | 19.5% | 7 | 41% |
| Liberal Party | 18.4% | 4 | 24% |
| Progressive | 11.2% | 4 | 24% |
| Labour | 8.7% | 2 | 12% |
More information about the 1926 Manitoba election can also be found on wikipedia
All About Voting 
How does the modern model compare?
I am not familiar with Canada’s current system. From a very cursory examination of the wiki page referenced in this post, it looks like they are using the same system they used in ’26.
Here is the 2006 data:
http://en.wikipedia.org/wiki/Canadian_federal_election%2C_2006