I want to purchase an acoustic piano that can become completely silent and use headphones too. The only piano that I have found is the Yamaha MIDI series. The particular model is an MP1Z. In acoutic mode, it is a U1, when in silent mode the keys no longer strike the strings and it plays a sampled grand. I am about to buy this. Does anyone have experience with this line or know of any other?

Good news: The silent mode works great.
Bad news: The sampled grand doesn't sound very good.
Good news: You can always add a better tone module (not necessarily a Yamaha) and use it via MIDI.
Bad news: I may be splitting hairs here, but the Yamaha disklavier MIDI system does not allow for the full 0-127 velocity range that is industry standard. The real-world effect is that the keyboard it is not as expressive when triggering a MIDI module.

(I'm not commenting on the piano, just the silent/MIDI function)

Thanks Steve. Given I want an acoustic piano with the silent function, I think I am constrained to the MP1Z in my price range (about $8,000 Cdn, $5,200 US).

I am also considering adding the DSR1 to provide recording and playback. I am posting a question in the forum on this unit and would appreciate your input if you have some.