Curious if I can use the Master Bedroom in the Dark Brotherhood as a safe spot to store my items? I completed the Dark Brotherhood and spent the money to upgrade the new location and added a Master Bedroom... Is it secure place to leave items?

Store something worthless in a container there, then wait for a few in-game days (like a week) and check if it's still there. We can't check which containers are non-respawning until the CS comes out.

I stored mine in the dark brotherhood initiates room and I didn't lose anything yet. I haven't tried the master bedroom but I'm sure its safe. Try what "wayman" said to be sure.

lol your signature is old