Not speaking specifically to the Jow Ga set, over the course of history and different wars in Southern China, other types of sword were used besides Butterfly Knives and Broadswords, more along the lines of a typical Machete.
After the founding of the Republic, and in Hong Kong, martial art shows were gaining in popularity, yet as "weapons" were prohibited for public use, readily identifiable "martial instruments" were used in their place.
That means that if you go to the "Luen Hing Music Store" to pick up some "weapons" for your performances, the only selection they have may very well be limited to Butterfly Knives and Broadswords (or maybe a Gim).
If you learned your set with a Machete, you might go with the "Butterfly" presentation, over a longer, rather more unwieldy Broadsword-type of instrument, especially if you'll be rolling on the ground (as this set usually does).
Just my .02, for what it's worth.