Originally Posted by
oneclick
No, it'll be even less than that because what you add to the bottom you take away from the top; the pivot remaining as the top of the seat lug.
As to the question I'm with the get-a-longer-one camp.
I consider seat height to be sacred. So seat top to top of seat lug doesn't change. You could go to a seat with deeper rails; allowing you to push the post down. The lever distance hasn't changed because the force location (you) hasn't changed.