If you have an Accuquilt cutter, how do you store the dies & mats? Are they hung up up or stored flat?

I just posted a picture of the storage bins I found at joanns...you should keep them up not flat.

Most of my dies and mats are stored flat in a drawer. I have the die rack but have too many dies to use racks for them all. I bought the Go as soon as it was available to buy and all of the dies that were available then. They have been stored flat since I bought them and I haven't noticed any problem. I have noticed the first dies seem to have better foam on them then the newer dies and the first dies seem to be sturdier then the newer ones.

Accuquilt suggests that the dies be stored on thier sides, not sure why.....its works for me with the in I bought.