Seems to me that this is all working with the assumption that the development is on a Linux box. When developing on windows or mac using a vm such as boot2docker you're going to need to somehow share your codebase from your host machine to the vm and from there mount it as a volume in the docker container.
Did you have to handle files created or changed by processes running inside the container being assigned the root user ?
Doesn't seem to be an issue. The files created inside the container and written to the mounted volume outside the container are the same user/group as the parent directory (outside the container), not root.