Always been a fair few mentions of counterbalances on here, and I see from all the bat photos that a fair number of members add them to their bats, but what I have always wondered about is the split over why.
I add 2-3 1-inch strips of grip under the grip on all my bats, but I do so because it sits nicely into the top of my top hand, and possibly because it helps with no grip slippage, especially if I have a bit old mow. I'm pretty sure the weight involved in 2-3 inches of chevron grip is insufficient to have any effect, and I've never really noticed any change in the feel of the bat after doing this.
I do understand that the general consensus though seems to be for a counterbalance (pretty sure that's the wrong word since the weight is still on the same side of any pivot point) where the idea is to add weight high up the bat in order to improve the pickup. This seems to be done by adding lead (other weights are available) to the knob of the bat, whether has lead tape or by hollowing out the top of the handle, etc.