Dangerous to your trim, maybe. Dangerous to your life? Not so much.
It is not speed, but difference in speed, which is dangerous to your life. I fear the one coming up behind me at a difference of 50+ MPH MUCH more than the one next to me doing a couple MPH different. Yeah, the guy next to me may take out my mirror or scuff my door, but the guy behind me may kill me.
NOT On a motorbike, the person next to you is as dangerous if not more so than oncoming traffic. when your travelling at speed on a motorbike a tap from the person next to you that doesn't see you can be just as fatal as a head on. Usually I am far more concerned about whether the person next to me has seen me, oncoming traffic is far easier to predict and handle on a motorbike, the driver that merges without indicating is nightmare that you need to be constantly aware of if you want to stay alive.