Cut a loop in around the top of your mesh, on the line where the inset is skewed(disapearing).
This happens because the normals of your projection mesh are averaged around the top, but it looks like you have an extra loop at the bottom to support those cut-outs. Thats why you don't see the same skewing on the bottom.
More info here: http://www.polycount.com/forum/showthread.php?t=81154
Adjusting your cage is a messy solution, and unlikely to give you enough control to match the detail on the bottom.
Messing with smoothing groups(and not using a cage) is even messier, and will cause gaps in the projection around hard edges.
Messing with smoothing groups while using cage will have no effect.
Additionally, you may want a supporting loop on either end of the mesh, as the bevels on the sides skew out further towards the ends.
timwiese: The top has the same bevel detail as the sides/bottom, as clear from the screenshot of his highpoly.