JJHACK,
The optimum barrel length for you is the barrel length that fits YOU. Shorter barrels swing faster and longer barrels swing slower. You need to choose the barrel length that fits YOU and your type of shooting needs.
Everyone is different in their shooting needs, so it's an individual choice.
Most of the shooters that choose a short barrel are using it for turkey hunting and need the shorter barrel length for the close quarters that they hunt. However, that does not include everyone. I prefer a 24" barrel because it swings quicker and I like that for ALL of my shooting/ hunting needs.
Longer barrels offer a longer sighting plane and a slower and smoother swing that some shooters prefer for "wing" shooting.
As for ballistic differences....there are approximately 10 to 25 f.p.s. of difference between a 24" to a 28" barrel, with the same ammunition. That's not enough of a difference for the average shooter to notice and certainly not a good enough reason to choose a 30" barrel when a 24" barrel is what fits you and your shooting needs.
Good luck with your choice!
Good hunting, Bowhunter57