The Seventh Taylor

Besides early PS3s there are various Blu-ray Disc players that feature SACD playback, including all Sony´s 2010 models. See this list.

Not all of them. Certain serial numbers did. Mine does not play SACD but I don't use them so it wasn't a problem for me. v8peters is right: If you've got a 60GB PS3 it should play SACD. If there's an issue with it you may want to check the troubleshooting guide of the PS3 SACD FAQ: http://www.ps3sacd.com/faq.html#_Toc177216818

Correct. See the PS3 SACD FAQ.

Even if gaming is unimportant to you I'd still recommend the PS3. It's a fantastic media machine (with video upscaling, audio upsampling, streaming capabilities, etc.), with new features being added with every consecutive upgrade. For me the only benefit of the Oppo would be DVD-Audio playback but I have very few DVD-A discs (as opposed to quite a few SACDs). The only other thing I could think of is its 'AV component' design i.e. it fits in a stack, against PS3 obvious console design

It definitely is worthwile. The settings are mostly a matter of taste though I'd say Bit Mapping setting 3 has generally generated the most favourable reviews. There's a handy FAQ about SACD on PS3 at PS3SACD.com. If I were you I'd try multichannel SACD through HDMI on the Onkyo rather than stereo SACD but again that's personal.