You already did the addon??? That's fast!! Thanks a lot, dougal2!!
A standalone addon is also great, because it makes it available to others users that don´t use Luxrender but use Blender for arch-viz. I think that this is so useful for who want to use blender in architecture that should be greatly advertised in Blenderartists forums and others sites.
The only glitch I noticed on the addon is that in Ubuntu Blender shows the two update buttons but on Windows doesn't. I tried to different builds and nothing shows.