FYI There have been some instances of the top bunk failing due to poor construction. There are threads on this forum about this and the poor warranty repairs of this. I believe one owner disassembled the bunk and added reinforcements to ensure bunk integrity.
I have inspected our Fuzion's top bunk and plan on reinforcing weak points. We do use it for storing light items (bedding, clothes, etc.). We won't let adults use it and in the unlikely event that small children use it, they will be advised that normal rough housing, bed jumping is a NO NO until the bunk is corrected.
However, we do have plenty of other sleeping options.