Just some additional thoughts on what should and what does not need to go in your safe.
Your cabin steward is unlikely to steal anything from your cabin because they would be first on the list of suspects. Disney would quickly see the pattern if items keep getting reported as missing from rooms cleaned by the same person.
The only other people who are likely to steal from you are other Disney employees, other passengers, and your roommates.
Other Disney employees and other passengers wouldn't risk entering rooms hoping to find things worth stealing. It would only be worth the risk if they know ahead of times that you have something in your cabin worth stealing. Keeping in mind that your cabin stewart props the cabin door open while they work on the cabin, if you keep valuables out of site, only your cabin steward and roommates will know what valuables are in your cabin.
The other way someone might be able to steal from your cabin would be if they entered your cabin while the steward had the door propted open. This would usually be because someone (employee or MAYBE another passenger) needed to ask the steward a question. Now in that situation, I could see where an unscrupulous individual might steal a small and valuable item they happen to come accross sitting out while the stewart's back in turned, but if they tried to pick up a camera or computer sitting out, the item is too large to risk going unnoticed by the cabin steward.
The last way someone might be able to steal from your cabin would be a maintainence worker that enters your cabin for repair work. While in your cabin, they might deside to look around and see if you have anything worth stealing. But if they tried to lift a camera or computer, they run a big risk of someone seeing them when they leave (and obviously it would NEVER look good for a Disney employee to ever leave a cabin holding a camera or lap-top computer. They could only risk taking something small they could easily hide in a pocket. And even then, if they were entering your cabin for legitimate perposes to begin with, once again, they become prime suspects if anything does turn up missing.
So in my opionion, it comes down to small valuable items should be kept in the safe to keep from someone pocketing the valuable should they somehow happen upon it. All other larger items are unlikely to be stolen if you just keep them out of sight so that no one has a reason to formulate a plan for swiping a large item from your cabin.