A break cue is tuned for the opening power shot rather than delicate position play. Stiffness, tip, balance and bumper construction may differ. It can still be used for other shots, but the feedback changes.
Check the rules of the event you play. Test rack spread, cue-ball control and repeatability—not noise. Power without a stable hit is not an advantage.
An extra break cue makes sense for regular play and focused practice. For occasional home games, one well-fitted playing cue may be the better value.