It freaked me out too, when I first started riding in groups to see people passing on the double-yellow. I don't think I started doing it with confidence until last year. With that said, I do it for all the reasons mentioned above. Here's reasons when I won't:

  • sight distance -- when I can see a blind corner coming up and know that even with downshifting and going hard on the throttle won't get me past the vehicle without freaking out the cage driver and myself. This goes for upcoming hills of any height, as well.
  • leading a group of fairly newer riders, or new-to-group-riding riders...unless, extenuating circumstances call for it, like a cager who seems to be completely oblivious to the world around him/her. In this instance, I'll stick out my arm when passing to let followers know it's ok to pass as well and will put my arm down immediately when I see any possible danger.