Commuted for 4.5 years in Los Angeles on a motorcycle, 50 miles to work and 50 miles back home (!), splitting lanes the entire time. Never went down, had lots of close calls of course. No one EVER opened a door on me (as is commonly thought), or threw anything out the window. Some idiot would shift over to close the gap, but then it would just be a matter of switching over to the next lane and split there and get away from the idiot asap.
I've been tempted NUMEROUS times to split up to the front at a stop light since it would save a ton of time, but have to resist just in case some unmarked cop is somewhere.
The difference between California and Ontario is that people are used to bikes splitting lanes in California, pretty much every bike does it, plus all law enforcement does it as well. I found that being between two cars was actually SAFER than being in a lane on my own where a driver thinks there's a space to move over.
That said, I would never split lanes here in Ontario, way too dangerous. Cars aren't used to it so they won't be expecting it, or you'll get some yahoo who wants to enforce the law and take you out by swerving over. Unfortunately the law would be on the side of the driver.