By all accounts Oregon fans and UT fans got along famously when they came to Neyland. Many were blown away by our hospitality. When it came time for us to travel to Autzen, Ducks fans took to their boards and told other fans of the experience they had here and asked Ducks fans to go out of their way to return the kindness. There was quite a bit of talk about this on their boards and how Tennessee fans deserved the royal treatment based upon how well they'd been treated and how the word needed to spread throughout Duck Nation.
I remember a few Oregon fans were worried that their fellow fans wouldn't be so gracious but from the reports I've heard by Vol fans who made the trip it was a great experience -- student section did some stupid stuff but overall they rolled out the green carpet for us just as we rolled out the orange carpet when they visited.
Tennessee fans and Oregon fans have a good relationship.
That all said, the PAC isn't like the SEC in terms of fan behavior -- we tailgate together, begrudgingly respect our SEC opponents, try to show guests a good time (minus the drunks), and even cheer our conference in post-season whereas they don't really have that kind of camaraderie. For us, football is as much about socializing before and after as it is the game itself. In contrast, they seem to hate all fellow PAC members the way a UF fan hates to see a good piss bomb go to waste.
Oregon fans have a reputation within their conference as being lousy hosts to say the least -- a lot of that is likely due to bandwagon fans jumping on due to their recent success. However, I doubt it's half as bad as the worst descriptions.
Regardless, they treated us well.