While the authors might be able to find a similar phenomenological agreement with more reasonable parameters, it will change all of their results and amounts to a substantial revision.
Walter (ref 7) describes the formation of “clumps” which are very similar to the structures describes by Shepard. Shepard and Sumner provide better images (Walter only shows sketches), but it might be worth mentioning that the phenomenon is more general. As I recall, Petroff et al. (ref 13) show similar patterns.