Just to see what would happen I installed a bunch of these packages on an Ubuntu 16.04 system w/o -proposed enabled, I then enabled -proposed and upgraded the packages without any issue.
I then modified DistUpgradeController.py in the u-r-u tarball so that -proposed would not be disabled during the upgrade process and upgraded to Ubuntu 18.04 without any issue.
Just to see what would happen I installed a bunch of these packages on an Ubuntu 16.04 system w/o -proposed enabled, I then enabled -proposed and upgraded the packages without any issue.
I then modified DistUpgradeCont roller. py in the u-r-u tarball so that -proposed would not be disabled during the upgrade process and upgraded to Ubuntu 18.04 without any issue.
Here's the list of packages I installed:
sudo apt install appstream bumblebee python3- django- countries dochelp dovecot-core fusiondirectory glib2.0 guile-2.0 hicolor-icon-theme ltsp-client neurodebian python-nevow octave packagekit pike7.8 pike8.0 shared-mime-info python3-sphinx postgresql-common tex-common python-wokkel xpdf yorick