The catch part of the lasso does add spin, but if a harder lasso gives more spin or not is debatable. If the string does not have time to slide through the non-dominant hand, you will be pushing the top sideways but no really adding spin. On the other hand, if it's too soft it might not press enough against the tip or move too slowly against it. So there is probably and ideal speed, which also depends on how you control the string in 3D. Having a longer stroke does add more spin. By the way, on the hop of the roller coaster you can lower your right hand to extend the pull.