A couple of points to remember here. First, a very high percentage of break ins are people looking to spend the minimum amount of time in your home and get the easiest things they can grab. These types aren't going to take the time to try an open a safe.
Deterring burglars involves more than just buying a safe. A house alarm, large dog, car in driveway, light timers and motion detector lights also play a part. Thieves tend to be lazy and cautious, so the harder it is for them to get your stuff, and more likely they are to get caught, the more likely they will move on to someone else. Also, the fewer people who know you have valuables, the less likely you are to be targeted.
Lastly, you are far more likely to lose your firearms to fire and/or water damage than theft, so make sure you address those areas as well, and make sure you have the proper insurance to cover you under any contingency. Most homeowner's policies cover a very small amount (generally $2000) for firearms and jewelry and nothing for cash.
