Olympus OM-D or Pen E-P3
My opinion is if you enjoy using the PEN E-P3 without a built-in viewfinder and other lesser features, I'd stay with that. A lot of times when a new camera comes out, there's firmware upgrades and all sorts of minor adjustments that could happen. It's also better to wait until the reviews comes out. So many people buy cameras before the reviews and occasionally they get "bit" with a less-than-desirable model. It's best to wait a while and just enjoy what you have. You can always get the latest and greatest Olympus model later (after thorough reviews have been made). You could keep or sell the PEN E-P3 then.