Ubuntu :: Defining Keys Under Compiz With Unity?

I'll come out and say I actually quite like unity, but it still needs a whole load of development. So I'm just wondering if anyone else knows how or why you can't bind Compiz keyboard shortcuts wile running unity. I'm trying to bind a shortcut (any) to Initiate a Window Picker for Window Group. If Unity is moving toward the Mac way of treating groups of windows that belong to the same program as an application it needs to have more options to manage those windows, being able to at least expose those windows would be a start. However I cant seem to put a keyboard binding for this function. I've tried <super>+<shift>+W and on a hunch that it was unity's Super that was messing it up <control>+<alt>+ and <super>+ and <alt>+W and <alt>+<shift>+W.