Ball Shifter vs other gearbox

[Priyesh69]

I am trying very hard to convince our mentor to buy a ball shifter. Right now we are using a cimple gearbox with two cims on each. He doesn't think that going from a 4.67:1 ratio to 3.667:1 will change something big. Plus,he think that a low gear will be useful to pass defending robot. Does someone have any more argument or prove that ball shifter are really useful. Is there a vid showing a robot with ball shifter passing through defending robot.