Unity Efficiency
It rather depends on whether one does multiple single window tasks or one or more multiple window tasks. Taylor T&M theory would indicate that Unity does work better for the former but worse for the latter than a Gnome 2 type GUI. In effect, Unity is a penalization of those who have to do tasks that require multiple windows in simultaneous use. There is a weak correlation between the size of the fraction of tasks that are multiple windows and the intelligence of the worker. In this context Unity is a dumbing down. At this point there is inadequate verified experimental data to substantiate the general claim that Unity is more efficient. Even so, the question of whether it is more effective is much more difficult to deal with. I am happy for you that your tasks are simple enough that Unity is more efficient for you. For myself, I installed U 12.04, used with a timer client for two weeks and then installed KDE. Subsequent data indicate a 0.17 reduction in mean time to accomplish tasks.