that would make sense if the z stacks were spinning. that would cause wobble. but because they are not spinning while the yoyo does, it is like sticking a ball bearing on a pencil and then holding the pencil with pliers at a 90 degree angle. does holding it away from the center of rotation cause wobble if the center of rotation is being held by something else? no.
i would get G5. more stable and it comes with zstacks. longer spin time too. but, it does play a little slow.
oh i thought he said he had tried them and liked them. yeah if you have not tried them, get a PGM. dont spend $100 on a novelty.