I'm inclined to agree, David. I was getting some strange and inconsistent color-shifting, and a commenter recommended the starter.

Keep in mind, though, that I was using very old chemical concentrates, so my first guess would be that my Part C concentrate is weak due to age. It's too early to tell currently, as I've only mixed up one 1L batch (the original, without starter). The non-shifted negs look perfect, though!