This is a no-brainer, yes it seems dangerous, but once you do it regularly it really is quite safe actually. People in cages don't see you anyway so always keep that in mind.
Now in places where cars are used to it, there's a better degree of safety since they tend to look first. However that in itself is misleading and never to be trusted since there is always the one pulling into your spot exactly at the time you're passing by, so never fall in complacence.
Where people aren't used to it mostly you have to deal with the jealous type that thinks you're stealing something from HIM. Like he's never speeding or rolling that stop sign and always using the blinkers... The key thing is it's not a race, and people should understand we're not getting ahead of them but rather out of the way. After all we're not all going the exact same place, and one less vehicle on your path also makes you get wherever you're going faster...
To each his own though, I understand why some people won't do it because it's intimidating, that's fine. Just be sure not to advocate in the other direction, some of us actually do rely on it.
For the record I don't do it anymore because I don't need to, commuting on semi-rural back-roads is nice.
