Gemmers really don't have any advantage. There are few things you can do with gems: 1) Finish something's training/upgrading instantly. 2) Get instant resources.
Gemming just means doing it the lazy and impatient way(Of course, without gemmers, CoC and it's developers would not be funded as well, meaning lower-quality updates). The only way a gemmer would have any advantage is if they got certain troops and features no one else did.
Aside from that, I don't think there should be any kind of new Barracks yet. The Dark Barracks selection of troops isn't complete.


