Addenda regarding the Duo-Art una corda and/or soft rail lift.

My 1922 5'4" George Steck had only the soft rail lift.  It worked
nicely to dampen the sound. That piano was replaced with a 1928
Steinway OR, which has both features: una corda shift and soft rail
lift.  Both used simultaneously really softens the output.  Yet I
rarely use this.  There has been no problem with hammer shaving or wear
from the una corda shift or from using the soft pedal while playing
manually.

I'm wondering whether the class of piano or its cost determined what
system was installed.

Ray Bauer
Lake Tahoe, CA