No proof at all that bat speed, bat power or willow affects the game on the field. However basic physics would tell me that a bat swinging through quicker would therefore meet the ball at a quicker speed. With all this every action has an equal and opposite reaction stuff I would imagine the ball would come off quicker obviously assuming all other variables were the same.
Ok newtons law of physics are right... For every action there is an equal an opposite reaction... Yep that is right!!!! I'm not going to argue with Newton
Ok that opposite reaction will include energy loss via vibration / twisting / elasiticity of the bat / heat etc etc..... you could swing the bat as hard as you like if it isn't designed / made properly [not saying that mongooses aren't] then your energy losses in other areas are significant enough for you to lose that initial gain of having a faster swing speed.
Ok now i said all that what you really need is, if you sticking with the design [and even if you are thinking of changing], is consistency in your willow and manufacturering processes if you feel you have that then fine.. Could it get better I think so but thats me... I reckon my own bats could be better, in fact I've only seen one or two bats I'd say "that is it... you will not get better then that"
Don't get me wrong I like the concept of mongoose... I would have love to bring something like that to market...
Oh I think that is enough