I own both. The Oppo has slightly better Blu-ray image quality, but not enough to justify the upgrade all by itself. And the PS3 is a much better streaming device than the Oppo, with more available services and a snappy UI.
I got an Oppo because it'll play anything I throw at it, does a better job with DVDs than the PS3, and has region mods available so I can play discs from other regions. But if you're really only interested in Blu-ray, Vudu, and Netflix, the PS3 is a great choice. That $500 would be better spent on another component.