My team dogfoods Ubuntu for Android every single day on the Nexus 4, and I'll say that it's performant enough to be a daily driver as a desktop replacement.
Edge has 4GB of RAM planned, and will run even better than the N4.
hows the camera for you? I use the n4 with android and the camera digital blur / tearing is pretty annoying. did you get around that or not use the camera much?
Edge has 4GB of RAM planned, and will run even better than the N4.