My favorite Piper story is Uller Uprising. I actually liked Hunter Patrol and feel it was probably less optimistic version of time travel than Time and Time Again and a send-off of the grandfather paradox. 

Just finished Lone Star Planet and agree that the satire was over the top. The characterization of the z'Srauff definitely was a bit speciest. In Ministry of Distrubance, the Thorans are described as terrier-like so are Thorans more disciplined, z'Srauff? 

The z'Srauff and Thorans were a likely inspiration for Traveller's Vargr and the Bolo universe's Melconians. 

Tim