This past Saturday I smoked 3 pork butts & 3 beef chuck roasts. Made a rub from Paul Kirks book and rubbed both the chucks & the butts. smoked everything together till internal temp was 190F. Everything pulled apart with the greatest of ease. :P
After pulling we mixed it all together. The results are excellent! However I must say I don't think that adding beef made it better, just different. Pulled Pork is awesome on it's own, adding beef gave it a different flavor. I would definetly do it again.