Once booted back into LXDE, more of the Gnome dependencies and heavyweight System Tools (and Games) can be removed with the Pure KDE command (minus the end part relating to reinstalling kubuntu-desktop)
If you want to maintain some of the potentially useful Gnome stuff, don't follow the pure KDE advice. This removes gksu, Synaptic, Update Manager and some of the other GUI controls for Network Settings etc. Nevertheless, I think it's better to get rid of them to keep things slim. Components can be added back in customisation at a later stage.
If you do run this command, reinstall LXDE again, just to be sure!
sudo apt-get install lxde lxde-common lxde-settings-daemon lxpanel lxpanel-netstat-plugin lxsession-lite lxnm lxtask lxterminal openbox obconf gksu libjpeg-progs miscfiles xli xloadimage slim