There is no doubt in my mind but GE is absolutely worth the $100. In fact the last time through IAD I noticed that 2 of the cockpit crew from my flight were also using the GE kiosk.
Not only does it allow you to bypass the long lines for immigrations but when you pickup your bag you do not need to wait in the queue to give the customs agent your declaration card. At least at IAD you go to the left side of the check point (adjacent to the wall) and go right to the head of the line and just hand the customs agent your receipt from the GE kiosk, that is as long as it does not have the dreaded X on it, and scoot.
