I chose the Quanset
I only load for rifle and shotgun and shoot very little during the colder winter months (no indoor range etc) so loading in a cold Quanset doesn't happen. I have the room to load in the house, but chose the Quanset for that little extra piece of mind. IF and it's very unlikely, something were to ignite my powder/primers I can live with the Quanset going up in flames. The cement floor is also easy to clean up the grains of powder that always seem to migrate, as opposed to carpet. I also store all my ammo and reloading supplies out there, about 200' from the house. The temperature swings are not what you would expect since it is fully insulated, and humidity in S Alberta is a non-issue.
This also works very well for when I'm developing loads (from April through October). I load a few, step out the Quanset door and I'm about ten feet from my bench and test firing.
Use what you have, safety first and enjoy. With good safe practices you have less to fear from reloading in the house than the explosive, flamable, poison etc. that every house has under the kitchen sink and in the Wifes beauty Storage locker (hairspray, alchohol, polish remover).