The other day during when we were training, one of the players was off to the Junior national championships. I played her, lost 11-9 but irritate it took me so long to start attacking but overall played well. At about 5-6 we lost the ball I brought back another but she wouldn't play with that and went and found the right one. Turns out it was a plastic ball which I may have been told but certainly had forgot about. But I hardly noticed a difference other than her backhand didn't seem quite as fast as usual and if anything a lot more of my shots particularly flicks worked on serves. Personally don't think it will have much effect. I only remember pros are using them when they crack.