The advantages outweigh the cons. I don't think there's that many ways to abuse the merger. If there are those should be banned for willfully exploiting, Those on Trifri would be happy for the easier AH sales as nova is weaker server and nova would be happy for the bigger AH
the way the server duplication worked was that duplicated gear was to never make its way into trifri from nova. duplicated gear retains its unique ID even if its sold or traded to other players thus I don't believe its possible.
However, Its hard to tell which server benefits. I don't think the problem with nova is that there's not enough stuff in AH. In theory, theres nothing wrong with Nova, just that the lack of pk means theres 1 less thing to do or worry about.
in my opinion, Nova seems to be lacking a social aspect. No matter how boring something is, so long as theres people to talk to and work with for a goal, it can be rewarding. In nova, i think the combination of a lack of people, lack of need to cooperate, the way new content is geared around hoarding and inability to share (im talkng about voxyon) is not helping.