I agree with Bryan Cather that the speed of closing of different sized
pneumatics in the same instrument is insignificant when compared to
the other variables.

One factor that may or may not come under scrutiny is the differences
in striking time resulting from the differences in applied vacuum.
If a very soft note is played in conjunction with louder notes in a
different range, in theory the soft note would be late.  I have never
been impressed with the rhythm reproduction of reproducing pianos.

My question is, did the editors ever take into account the need to
micro-manage the rhythm in Duo-Art recordings?  In the roll, "Warum",
where soft playing has fine differences, the rhythm never seems quite
"on".  How does applied vacuum factor compare with the potential error
of different sized pneumatics?  And how many angels can dance on the
head of a pin?!

Bill Chapman