Of course, to me the most useful feature would be if it could convert composite to s-video or component, and s-video to component. Not because it would increase picture quality, or because I lack inputs on my TV, but because it would let me run a single cable from the 950 to the TV, and because I'd never have to hit the TV/VIDEO button to switch between the myriad of inputs on the TV. Just switch the audio input on the 950 and the TV switches too.
I don't see any use in being able to downconvert signals, except if you maybe wanted to connect the 950 to a very old TV that didn't handle S-video. I don't see that being likely, though.
But then again, if the 950 had a really really high quality comb filter, there's the possibility it could do the job better than your TV could and would therefore actually increase picture quality.
I doubt the 950 will do this, given its price point, but maybe the high-end pre-pro will. Do you think they'll call it the 850?
Another useful feature. Composite and S-video inputs for ALL audio inputs. I don't know about you, but my CD player DOES have a video-out jack. No, it doesn't play DVDs; it uses it for on-screen menus only.