This is a test using only a SunSky light, added it into the .lxs file by hand and deleted the other lights from the .lxo file. It's been rendering for 12 hours overnight and I'll leave it to render today while I'm at work.

The scene is Stonemason's Warehouse by the way.

Software: OS X 10.8 - Poser Pro 2012 SR2 - Luxrender 1.0RC3 - Pose2Lux
Hardware: iMac - 3.06 GHz Core2Duo - 12 GB RAM - ATI Radeon HD 4670 - 256 MB