Phil,
    I am working on a project now for solenoid player.  Yamaha and P/D
at present are at 500 millisecond delay.  This is based on the
frequency of the (PWM) the solenoid is fired at They use this level
also to sink other MIDI channels to channel 1 This delay is on the
disks.  I have a table developed from a dB level on the piano then
assigning MIDI level The speed of the key is noted at the dB levels
and my table looks (for example) 80db " MIDI velocity 40 " key speed
96 milliseconds.  I have discovered this table is close to the work
done by Stoddard and the spark chronograph on hammer velocity.  Their
is at present no standard set for MIDI velocity and piano dB levels.
In my research so far I have found hammer velocities change from piano
to piano but the key speed did not Their is much to consider on this
subject but the work done on Ampico and Duo-Art and Welte should be
studied and considered.  The Piano is based in most part of empirical
methods of design.  To achieve the play back in a MIDI base language
the reproducers of the past should be the benchmark.

     D Dusenbury