When I researched mine, the vulnerability that I read about was knocking it over and sledgehammering the top cap welds. The report I read suggested most RSCs are easily opened without ever messing with the doors, going for the vulnerability, not the strong point. ANY security device is about the time and effort needed to defeat it, and the risks involved in the process, not about truly burglar proofing your stuff.
This is true. Most RSC's the door is the hardest part. Experienced theives will attack the thinner guage steel on the sides with a sawzall, or even something like a wood splitting wedge and a sledgehammer to cut a hole.
No matter how good the safe is, it's always a good idea to place it in as tight of confines on all sides as possible to prevent access, or the room to swing tools or get leverage.
However, bolting it down prevents the less experienced from trying to tip it to pry the door, or some actually are good at it and do find using their body weight to pry easier than swinging/cutting. And tipping it can give access to the back for the cutting/piercing attack too.