The longer the sling speargun, the more precise it is for timid fish in a long distance. On the other hand, with a shorter sling speargun you can move more easily.
Spearguns made of composite material are very stable and precise. Tubular spearguns are also quite stable, but they don't reach the rigidity of the composite, which affects the stability of the arrow.
Pneumatic spearguns can be used for bigger fish. Especially for the ones with thick bones, the arrow needs to be heavy enough to be able to penetrate into the fish. The arrows of the pneumatic spearguns are heavier, and they hit harder. Naturally, these spearguns can create greater power for launching, too.
In pneumatic spearguns, the length means efficiency, stabbing power, and preciseness.