I got almost the same graph of @organofcorti two weeks ago. (from my own open-sourced simulator)
However, 100% agree with @deepceleron

When we have more proportional pools, efficiency doesn't 'seem' to be decaying because we have more chance to hop into < 43% pool all the time.
Earlier share is always more profittable, slicing reduces profit in the long time, and a share from > 43% pool is less profittable than a share from pps pool.