How to store my O/U

I do not store ANY of my guns in a case whether it be takedown or not. I always store my guns in a safe with a goldenrod or even a metal gun cabinet with the moisture evaporator you re-activate in the oven is good.
I prefer takedown cases over full length for transport mainly for ease of transport. It is a pain to take the gun apart and put together every time but the package is much easier to get in a crowded SUV. The full length can give you a place to lay your gun safely when not near a rack.

Burnt Powder,
I've gotcha now. I was getting lost in the translation of your word store as opposed to transport. You wont believe how many people actually store their guns in a zip case. I do know of some target shooters who do store their guns in a take down case inside their safe but I like mine to breathe.
Break 'em All!