I'm wary of supporting positive reviews remaining in the ad threads if negative ones are being put elsewhere, especially with the risk the negative reviews could be hidden behind the membership wall of the Hog Pit. It might be easy to join but it isn't something a new member will know to seek out unless someone held their hand into discovering it.
I think keeping the ad threads for Q&A as well as for linking to revelant threads, whether in this subforum or the Hog Pit, is the correct course of action to avoid bias.