I think the next thing I'd like to do is have the ripples fade out earlier than move until the edge of the screen. (Because I want their motion to be slow, but the time of the effect to be short.) I suspect I need to use time warps to do that?
I'm not 100% sure of the effect you're looking for based on your description, but if you'd like to fine-tune the transition speed then you'll use warpers yes.
