has anyone actually measured thier bat speed with one. It’d be a very easy way of proving the theory.
Too many variables to be able to draw a meaningful conclusion, given the need for a human to swing the bat.
There is honestly no scientific reason why adding a counterbalance would increase bat speed, it just doesn't make sense. It might be able to make it pickup lighter (if you believe that school of thought), but to make a meaningful difference to the distance a ball travels? I really can't see it myself.
But hey, whatever works for you, works for you. There needn't be any logic behind it if it makes you feel as though you hit the ball further, cricket is 100% played in the mind.