Robert,  What you have there is rare in that the belly cloth is still
intact, and this indicates the instrument has never been "fiddled
with."  Nowadays this is rare indeed.

A Steinway Duo-Art equipped grand piano has been specially made by
Steinway to accommodate the playing mechanism with longer keys to
accommodate the roll playing mechanism above the keys, and other minor
(compared to the key change) modifications.

As to how many 'O' models survive, I can't answer, but I can tell you
that removal of the player would be a loss historically.  I would hope
you could find someone who would trade you a non-player Steinway, since
you are of the strong opinion that it is limiting the dynamics of the
piano.

In today's piano marketplace, I can't tell you if the player unit
adds to the value of the piano monetarily, but it does add value to it
historically.  You have something unusual there, please don't desecrate
it by giving it a lobotomy.  I do applaud you asking this group first!

David Dewey - RPT & Player Piano Restorer
Oroville, California