I don't have UHD playback capability yet, though I'm getting close. Still running a 60" Panasonic Viera plasma monitor coupled with an Oppo UDP-205, a NAD T758 AV receiver and a set of Hsu Research speakers. What's holding me back from upgrading my monitor? 3D! No 3D = no new monitor. For me, the ability to play 3D Blu-ray films – a most enjoyable experience – outweighs the incremental enhancements to picture quality that UHD affords.
But… if I ever do get UHD, it'll be discs all the way for me. Love me my uncompressed audio soundtracks. As an ex-broadcaster, I really appreciate what a good sound engineer can do, and I wanna hear every bit of what's on that track. Plus, as others have said, I enjoy owning my films. Don't wanna have friends over for a movie night only to discover that the film I've been looking forward to all week is suddenly no longer available. Or needs to be repurchased. Or won't stream in HD 'cause so many people are streaming right now. That's absolutely unacceptable.