Will Eley asked, "... what are the advantages and disadvantages of
these systems?"

As Robbie noted, this gave Wurlitzer another control or note for the
same number of trackerbar holes.  That is the difference from a
builder's viewpoint.  It also required Wurlitzer to make a reiterating
beater mechanism with an incorporated valve, while the B.A.B. uses a
simpler mechanism.

From an arranger's point of view, the B.A.B. system allows much better
control.  It allows a single beat, reiteration at a variety of speeds,
and creation of interrupted multi-beat sequences.  It also requires
much more work to produce a drum roll -- each stroke must be separately
marked and punched on the master.

With the Wurlitzer system, an elongated hole (either on the master or
due to roll damage) results in unwanted strikes.

Wallace Venable