I'm also considering to try out LightUp once I have enough time (and "ready" models to test it). Note that it has a trial version (AFAIK 1 month) so you don't risk anything giving it a chance.

Here is a topic on the LUp Forum I was browsing yesterday (in fact, it was for a different reason but then the same thing you're contemplating on came to my mind). And here is a video by Adam (author of LightUp) that demonstrates some workflow from LUp to Unity:

[flash=500,400:1gxuoxhv]http://www.youtube.com/v/eNI2RjNsRwY&hl=en&fs=1&[/flash:1gxuoxhv]