Andy, the MIDI-to-MIDI-piano via Internet would work if done the way
audio is now transmitted using Real Audio technology.  Strictly, this
is not real-time.  Real Audio sends music data in digital "packets" and
the receiver's buffer memory stores them and begins to play immediately.
In the time it takes to begin playing, a new packet is being sent.
There is a slight delay.

I have never had success with Real Audio, probably because my computer
has an insufficient cache to store enough packets to allow for a
continuous stream of music data.  When I use Real Audio the music plays
a few seconds, stops, proceeds, stops, etc.  Very poor.  This is partly
due to the nature of the Internet bottlenecking (bandwidth) problem.

MIDI can be done this way (with an appropriate program -- contact the
Real Audio people and suggest it), but it might work a lot better since
the data, unlike with Real Audio, is not from a digitized recording of
music, but is rather a digitized record of simple music events -- which
key struck and how fast, pedal duration, etc.  This wouldn't overwhelm
the receiver's cache, and might flow more smoothly over the congested
net.

Another possibility, in theory, is that MIDI is not the best medium to
convey the music across the net.  It would be, rather, Java -- or, that
is -- Java as it can translate MIDI.  Java is already designed to allow
for (cross-platform) real-time events -- such as a stock price ticker,
news wires, chat rooms, etc.  The problem is, Java sucks.  And so does
the Internet -- at least for now.

Regards,

Johnny Lite