I did the Bikesafe thing with a couple of motorbike cops, and they said (about motorcycles) that because it's so much more dangerous they would always try to be moving faster than everything else around them so that they didn't have to be worried about things behind them so much. They were perfectly happy with 5-10 over the limit on a dual carriageway.
Helped me with my observation no end, that course, I think.
The other thing they said specifically that at the end of the ride they'd ride at their own speed, on a new CBR600, don't try to keep up beyond your skill. I scared myself silly on my V-Strom 650. The other thing I remember about that ride was that one of the other guys was on a brand new 1000cc Ducati and he couldn't ride for toffee.