I still get pissed every time it happens. If I'm moving fairly fast (mid 20's), and cars are passing me to close in a 35-40mph zone, and I have no shoulder, I may take the lane on my own--especially if there are two lanes moving in the same direction. I don't do this to hold up traffic, but I feel that if traffic is forced to slow down and actively move around me I'm safer than if they are just whizzing by paying no attention. Its obviously best to try not to be on busy roads without shoulders, but sometimes it just can't be avoided. A helmet mirror can be good and bad. I feel that I am safest paying attention to what is in front of me and making sure that I have enough room to do what I need to and stay safe (here's where taking the lane comes in).