I've personally never been too fond of threaded view, it seems to cluttered to me, and I see people read all the replies, and then post a reply to the last one in the thread, when they meant to reply to the original thread.

I don't find flat confusing at all, as usually most respones are to the originator, and when they aren't they either have quotes from someone else, or the person states who they are talking to.

But thats just my opinion...