I faced the same choice last May, and chose the Onkyo's big brother, the Integra DHC-80.2.

I'm not in a position to wax rhapsodic on the superior quality of XT32 over XT, because I never had a unit with XT in my listening room. But I've got an odd-shaped room, with uneven and tricky corners and a slanting ceiling, and I can confirm the XT32 does a remarkable job of accounting for it all. Running an Outlaw 7700 through the 80.2 gives me a huge soundstage, and truly allows for eyes-closed where-are-the-band-members-standing listening.

My sound quality is excellent, regardless of source component.

And as for another recent hot topic -- the lack of network streaming on the 978 -- I can report this: The 80.2 allows me to hook the unit via Ethernet connection directly into my home network. That allows easy access to the high-res digital sound files that reside on my computer in the next room without needing a Squeezebox or an AppleTV. The 80.2's DACs are Burr-Brown, if memory serves, and while they're not ESS Sabre, they do quite nicely.