I just think steering people towards the Streaming APIs is a complex solution to a simple problem. In my testing, it appears the search endpoints can now be used since the results in 1.1 now include a valid in_reply_to_status_id.
(And, hey, since I haven’t said so anywhere else, the changes in the 1.1 API are fantastic: so many improvements, but getting real Tweet objects from a search has to be at the top of my list.)