Image on top was V5 demo render 640 x 480, 1 point light placed roughly above the skull, no atmosphere. Default GR setting, Ultra render setting, time 4:43 Image on bottom was Lightwave 8.2, 640 x 480, 1 point light placed roughly above the skull, no atmosphere. Default radiosity setting, Enhanced Medium antialiasing (13 passes), time 5:57. Please recommend more comparison settings for me.

For a start, I would try to put the spotlight as close to the same position as possible. Direct lighting can have a strong impact on the way the scne looks. Also, default settings can mean very different things btween two different rendering engines. In this case things like Gain, Number of samples, balance between ambient and cast light... It would be good to try and understand better what the default settings mean in both software and try to get them closer to each other.

It is evident by the highlights on the skulls that the two main lights are placed in a different position. Not just slightly different: decidedly different. In the Vue scene the direct lighting stops at exactly half the skull, creating what is basically a backlight ("silhouette") situation. In the Lightwave scene, the direct light stops at 2/3rds of the skull, thus enlightening most of it. At least 80% of the difference between the scenes is just that. The rest is certainly how you did set up the parameters.

Yeah, thing is the settings are so limited in Vue and so complex in Lightwave, it's hard to get a real feel other than trying to find 2 pics that look similar and comparing the times. I did a different set with cornell boxes, and I set V5 as high in quality as it would go for radiosity and rendered at Ultra level. took aound 6 hours and 5 minutes. I rendered the same scene in lightwave (this time i had geometry right by the light so it was in almost exactly the same position)and set the radiosity to 5x15 (little above the default 4x12) and set the AA to classic medium. After 3 hours it wasn't done with the first pass, so i called it quits for the night. so far, i've seen that vue is quicker, but lightwave is a little more accurate.

If you're using radiosity to get a feel for quality of renderings, you might want to place the skull on another object, like a cube or a plane, something that will bounce light up.