I see, I focused on how to deal with such a "see previous changeset" comment, when the question was really about whether there is a need to make such comments.
Answer, just like with the non-changeset oriented workflow, it depends. If the new PR update deletes the associated lines of code, there is arguably a need for those types of comments to be manually added with the current interface, but not so with a changeset oriented interface.
I like the append only nature of a changeset oriented interface.
But I find this type of conversation quite fiddly to do in pure text without reference to examples and the actual use of both styles, so forgive me if this is still unclear.
