I think there are two separate questions here: what is more successful, violent or peaceful protests; and, what is more successful violent or peaceful revolutions/uprisings.

I think it is all relative, especially since you're unlikely to have a completely peaceful revolution and sometimes the violence follows the revolution. I think the October Revolution can be said to be relatively peaceful. I think there was a lot of show of force but mainly the soldiers under Kerensky deserted or failed to respond to the red guard soldiers of the revolution. But for the revolution to be successful, many soldiers were earlier slaughtered on the battlefields of WWI and thus ended up deserting. They weren't slaughtered in the name of the revolution but their deaths were necessary for the revolution to take place.

Like any successful revolution, the October Revolution heavily depended on politics, timing, and strategy. I wouldn't say violence is a key component of a revolution, or a necessary one, but often follows strategic requirements such as neutralising opposition who may stand in the way and gaining access to communication facilities or important buildings.

I've always wanted to read a book called Technique du coup d'etat by Curzio Malaparte but I have never found an English copy (that isn't a PDF), supposedly it is very good and gives a solid overview of the strategy behind a successful coup d'etat. I like his other, fiction, works too.

Source: Ten Days That Shook The World - John Reed (October Revolution).