In reply to Spencer Chase's comments about graduated pneumatics
and longer closing times of larger pneumatics, I'd suggest that the
difference in the time it would take for a larger pneumatic to close
would probably be so insignificant that it wouldn't matter.  The
difference in size would have more effect in the power the pneumatic
produced than how long it took to close.

If differences in the size of striker pneumatics made a significant
difference in how quickly they closed, there could then be no such
thing as a standard 88-note roll, for each manufacturer's differently
sized striker pneumatics would have reacted differently to it, with
unpredictable results.

Any pneumatic small enough to fit into a player stack will be small
enough to snap closed in an instant; and variations in size are going
to have more of an effect on power than on closing time.  You'd have to
get a pneumatic the size of an accessory pneumatic before you start
worrying about it not closing in an instant under normal circumstances.

Bryan Cather - Piano World
Alton, Illinois