Having just gone down this road, here is the tech stack I used for putting together a scientific conference paper: emacs / org-mode / beamer / beamerposter.sty. I had to do a bit of reverse engineering from tex back to org-mode to determine the proper org-mode properties to have the beamer layout I wanted -- if that makes any sense. I also poked around in ox-beamer.el. In addition, I used Omnigraffle and the Gimp for graphics. I am happy with the end result, and the original org-mode file is clean and manageable. And, yes, less verbiage, the better for conference posters.