Is the camera going to be fixed in position or moving? If it’s going to be moving then it’ll be better to shoot the “green man” against the green screen (background), but by green screen I’m really using the term Chroma. Now in this particular case, I would suggest using two different Chromas, either have a blue man suit with a green screen or a green man with a blue screen. In both escenarios you would also need to think about the actors wardrobe as to avoid having problem keying the man and the background, your Chromas.
If they are really good actors it would be advisable to shoot the actors and set and then shoot the green man moving the objects. You have to be careful, still, about coordinating actors, actions and green man. Also be aware of the spatial limitations of the actions, i.e. the camera angle, the position ob the objects relative to this angle and the position of lights and actors in reference to the aforementioned.
iMac 27 inch (Late 2011) • 3.1 GHz Intel Core i5 • 16 GB RAM • 1 TB HD • ATI Radeon HD 6970M 1024 MB • OSX Yosemite • Adobe Creative Cloud 2014 • Maya 2014