L297/L298 Question

I notice that the L297/L298 combo has the ability to
be operated in two basic modes. When the Control
line of the L297 is low, the L297 chops using the
Enable pins on the L298. When the L297 Control line
is high, the L297 chops using the Input lines on
the L298.

Chopping the L298 using the Enable line, causes both
the upper and lower transistors to turn on at the same
time; where as chopping using the Input lines causes
only one of the H-bridge transistors to turn on and
off (probably the upper H-bridge transistor.)

So here's the question. What are the advantages and
disadvantages of chopping using the Enable vs. Input
lines?

Any insight would be greatly appreciated.

Thanks,

-Wayne