Well, let me tell you my experience!
When we moved I took apart our 5x5 Expedit shelving unit. When I had to put it back together, the heavy top shelf turned out to be bent upwards in the middle. It was only a few centimeters.
I decided to unbend it with my foot, and through the resulting hole I found out that the Expedit are actually cardboard inside :)
Still, it's perfectly fine (there's books on top of the hole anyway), and straight again.
I picked the wrong colour on my 5x5 expedit for one of the 30 kilo boxes, and spent this Saturday carting it 2 u-bahn's and a bus back and forth on my shoulder to change it. I hurt. But it looks very nice beside the desk.
Well, let me tell you my experience! When we moved I took apart our 5x5 Expedit shelving unit. When I had to put it back together, the heavy top shelf turned out to be bent upwards in the middle. It was only a few centimeters. I decided to unbend it with my foot, and through the resulting hole I found out that the Expedit are actually cardboard inside :)
Still, it's perfectly fine (there's books on top of the hole anyway), and straight again.