Looking at this as a piano technician's standpoint, I prefer the
Ampico in a grand piano, as it is much easier to service the piano
action than the Duo-Art.

The piano action in an Ampico grand is easily removed without
disconnecting hoses and linkages.  In the Duo-Art grand, unless it is
a very late model, it is a major task, because one must disconnect the
junction blocks, and mechanical linkage before the piano action can be
removed for servicing.

In upright Ampico and Duo-Art pianos, there is not much difference in
the difficulty of player action removal.

Bruce Clark