Local samples changing the energy amount in your material? Dont know if it is related but I have seen this before and reported to both Autodesk and Mental Images...
In my case it was related to the use of Lens Shaders. When you have ANY lens shaders in use your local samples mess up the behaviour in your shaders, fancy right? But then you will tell me "but I dont have any lens shaders in use". Well it seems that Softimage does gamma correction in the render preview through some sort of hidden lens shader. This seems to affect ALL sampling modes in MR. Here is a thread with some more details, image debugging, and my concerns being downplayed by mental images crew and fans (what?!): http://forum.mentalimages.com/showthread.php?9103-Energy-Inconsistency-with-local-sampling&highlight=
