The pie rule merely prevents the pie-slicer from cheating; it won't
magically make him any better at game design.
If you have two players who both understand the game very well and your
problem is that neither of them trusts the other to create a fair initial
position, this will solve your problem.
But if a designer already intends to make a balanced game and is having
trouble with the execution of that intent (which is the assumption I see in
most discussions about how to balance games), this doesn't help you at
all.