A few days ago, I was lucky enough to have one of my posts shared to Kinja Front, which retitled it and added a new introductory paragraph, something we'll all soon be able to do.
When my Aubrey Plaza post was shared to Front, Ken referred to her little seen YouTube as "rare" in his new introduction and especially after the Front version was shared to Gawker, Ken's wording prompted a few people to question his choice. These were responses that I received because it was originally my post and for which Ken may not have received any notification, at all. (I believe this would also be true, if someone were to reblog to Sidespin, a Groupthink post. Though we won't know for certain whether there's dual notifications until we can try)
If, for example, say someone on Crosstalk were to reblog Hamilton's Gawker post ranking fruits and in their introduction, they declared another fruit tops, if there's a conversation resulting from the reblog, there could be several comments saying that the new rankings were nuts. And let's say that someone else reblogged it to Groupthink with a different ranking, then a third person reblogged it to a food Kinja with recipes and a fourth reintroduced it via a fruit industry blog, the original post would be littered with comments responding to stuff and rankings Hamilton didn't post and depending on which door you use to get to the comments, there could be topics which leave you perplexed. (Fruits ranked reblogged as the best fruits for sex? Is this post fill? Which ones can you buy in Boise?)
Don't get me wrong, I actually like the idea of reblogging with different headers and introductions — though I can also see where it could get abused — but I don't really see how they'll add to a conversation without having differentiated comments for each reblog.
Not to mention that for example, say someone who doesn't like a person's blogging style were to reblog one of their posts, then people start responding to the reblog and the original blogger takes offense to the critical comments and block people from the blog. (Maybe they're working their way down the notifications, where the share would be at the bottom of the list) Plus there's the whole thing about grays and people having approvals for different blogs.
I really think reblogging could use different (secondary) comment streams.