Quebec separatism is a tricky matter at best, for it is not clear what that province would gain by becoming a country unto itself. It would be quite small and not powerful. But even if that might benefit some, violence is only going to throw a pretty peaceful area into turmoil and fear so that their cause seems unworthy.
While violence would certainly bring renewed attention and urgency to the Quebec separatist cause, it would also result in wide condemnation among the Quebec populace as well as the international community. This would thus not advance their long term goals. A better bet would be to express their desires more visible through protests and marches, yet refraining from physical violence.
No, I do not think that they would get any better results from using violence to try to get their points across. I think that what they need to do is get some really smart people behind them, who are great public speakers and can convince others to join the fight.
I think Quebec sepertists need to all just chill out. Quebec is going to be just fine. Of course it will change over time - everything does. But violence wouldn't help here. It would just cause chaos and the end result couldn't possibly be a positive one. Canada's one of the world's finest countries.
I do not believe advocates for Quebec separatism would gain from expressing their desires more violently. Violence rarely, if ever, solves problems without retribution and no one should it expect it to do so. Peace protests and activism that upholds peaceful methods are far more effective and humane in the long run.