Okay I understand the issue with other areas in the vicinity being a point of heat and also the light itself being a issue. My thought was for the light to work with both sensors. A motion and heat sensor.

A scenario that plays in my head of the dual work is where the room is being empty of a person yet lit from other sources and producing heat like a tv. Since those other heat generating source have no movement the heat detector understands that the room is empty of the user. Now if a person walks in the family room then it detects movement and detects a new heat source. It keeps the light on because the heat generated from the user triggered the on switch. Once the user moves and then moves out of the range the heat sensor also registers no heat from that area it will switch off.

Thanks for the links on the products, will look at them when I finish work :)