Having worked as an f/a for a Canadian charter airline operating 757s on long (and very long) transatlantic flights, I know why passengers are ready to fly charter rather than chosing a scheduled airline: the price! It's as simple as that. There is also the fact that Canadian charters (Canada 3000, Royal and Air Transat) offer direct flights to many European cities not served by scheduled carriers. Air Transat, for example, flies from Toronto to Aberdeen, Scotland! No sched would ever operate that route. All in all, there are several reasons why people chose charters airlines.
To Kevin: As for your BA ticket, no, Canada 3000 will not be responsible for your missed connection as it is only responsible for your Canada-Manchester flight. Check with BA to see what their policy is.
Hope you have a nice flight on C3. You might even get to fly on one of their newly acquired A330-200s which, it seems, offer more leg room than the 757s.
Next flights: YQM-YOW-YOW / YQM-YYZ-CPH-YYZ-YQM / YQM-YUL-LYS-BRU-YUL-YQM / YQM-PUJ-YQM