My bike is a 2009 Jamis Aurora Elite, so I believe the hubs are Shimano Tiagra 32H hubs. The previous cassette was a Shimano M770 11-34T, so the replacement cassette has exactly the same configuration, just a lower end model I think. I believe I read about the problems with the PG950 cassettes off bikeforums.net from a google search, but I could be incorrect.

Anyway, the guys at the shop said that the cassette was okay, but that the chain was really stretched, and that if I changed the chain then I needed to change the cassette and the chain ring at the same time, otherwise it wouldn't mesh well.