The 5 DHC setup will have higher initial burst DPS, but damage will fall off once energy drain is factored in on subsequent shots. This weapon power reduction can be offset by various set-ups like Omega Weapon Amplifier, the purple DEM DOFF, or EPTW's.
The Romulan torpedo set-up won't have enough to breach damage output to shields without other energy weapons being present.
The Cutting Beam will not be effective until the target's shields go down, but it is still very good otherwise. It does not work with cannon-abilities, but it does excellent damage when combined with the Borg space set tractor beam.
Looking less for the obvious observations but instead for some mathematics on the topic.