- I believe you may have confused the sponge hardness with top-sheet. To my knowledge, the top-sheet role is to create spin by applying friction and the sponge underneath that is to create the trampoline effect.
- I have used Z3 for two weeks now, and my experience seem to differ from you. I love the huge trampoline effect and with ease the ball goes over the net.
- I had used Z1 on FH before, while it is amazing on FH during stroking and multiball which let one feel like they are pro hard hitter like Dima / Franziska / Aruna; it is a nightmare during game-play. The ball fly here and there. Z3, being the tamer version that I use it on my BH and to favourable effect. When blocking & pushing the ball, it seems tend to stay on the table rather than flying here and there.
I've used z3 for 2 years now, it goes rock hard and loses much of its grip within the first 6 months, mine is dead after 4, yet I do play 5 to 7 times a week. But still, it's supposed to be a flagship rubber, Tenergy lasts far longer.
The sponge is to create speed and a connection between blade and ball, it also aids the deformation of the topsheet, hence how people say elastic sponges, etc.
I never said that the Z3 doesn't have a catapult effect, it's a rocket. The thing is that the ball doesn't easily dig into the sponge because the topsheet has so much tension that it feels rock hard, yet that's why it's so fast.