In 1969, I was looking for grand-reproducing pianos in the Los Angles
Wilshire district.  This was one of the places many famous people lived
before Mary Pickford started the movement to Beverly Hills in 1919.
Being in my mid-twenties, I used to knock on doors in both areas
looking for reproducers, and a few famous people showed me their
pianos.  Victor Heerman answered at one house in the Wilshire district,
and I ended up purchasing his Steinway OR Duo-Art for a thousand
dollars.  See  https://en.wikipedia.org/wiki/Victor_Heerman 

A few years later, I decided to sell it with an ad in the Los Angeles
Times.  A famous concert pianist came to look at it, and his fingers
keep hitting the fallboard.  I also had a Knabe Ampico in the room, so
he tried it.  His fingers didn't hit the fallboard.  When measuring the
black flats on the Steinway Duo-Art, we discovered they were a bit
shorter by an eighth to quarter inch!  Therefore, he did not purchase
the piano, and that was the last Duo-Art I ever purchased.

I have never seen a discussion about the flats being shorter, and on
which Duo-Art pianos or in which years this occurred.  As I recall, my
Steinway OR was an early model.

Jim Miller's article about "Concert Grand Steinway Duo-Art Reborn As
Ampico", and how the concert pianist noticed the different feel of the
keys because of the length of keys has caused me to come out of my
shell and bring up the topic.

An added note: Victor Heerman tried to get me Mary Pickford's Knabe,
but she was not ready to let it go.  You might find this December 5,
1925 picture and article about Mary Pickford and owning a Knabe Ampico
interesting.

http://presto.arcade-museum.com/PRESTO-1925-2054/PRESTO-1925-2054-12.pdf 

Andy Raymond