I have to admit that the left one is Modo and the right one is Maxwell. Sorry guys
About the surfacefinish of the centersphere, yes it's different but the difference is still marginal and it doesn't matter that much in a test like this. That artifact you are talking about is not a artifact, it's a airbubble near the surface of the main sphere. If you are talking about the line on the floor pointing towards the lower left corner, it's not a artifact, it's a seam in the floor as the testsubject is originally placed in what is a cardboardbox model. That's where the seam originates from.
Maxwell rendering - 6 hours, 22 minutes, 54 seconds (
but it was clean much earlier)
http://maximus3d.se/mxw/Maxwell_candlewax_6h22m54s.png
Modo rendering - 1 hour, 8 minutes, 19 seconds
http://maximus3d.se/mxw/Modo_candlewax_4.png
Keep in mind that the Modo version required more tweaking and testing to reach similar results to the Maxwell version, this time should be taken into consideration if you compare the rendertimes.
/ Magnus