Went for the electronic lock safe myself. All safes can be hacked including the mechanical ones. There is a video of a guy out there with a HUGE magnet that he uses to unlock safes. It's a deterrent to keep the average thug out but also allow you to access it when you need to and preferably as fast as possible. I can get into mine in about five seconds from a dead stop. How long does it take to get into a manual one.... And some of the small safes including the manual ones can be defeated with a screwdriver and a twist of the wrist or some bare hands as the doors or cases are flimsy enough to tweak the lock and pop it open. No matter the safe it should be secured to the floor and/or wall with hardware that is difficult to defeat. Mounting a safe into a concrete floor in a garage with bolts that can be pulled out or broken when the safe is backed into isn't going to do much good when the thugs open the door to the garage and back in with a truck.
Also the electronic safes generally come with a key as a backup. I have one that was sent about 1000 miles away so a family member can access without searching or hiring a smith to do it should something happen to my wife and I and the other would be a HUGE PITA to find unless you knew where it was to begin with.
I do have to agree that the safes are made for nothing more than a 22 or an air rifle. Get a couple decked out AR's and that 18 gun safe is a four gun safe. I am about to the point where I am going to strip the shelving out of mine and build it right and get rid of the extra notches for all the rifles to rest on that do not work anyway. Also want to add some door storage for pistols since the shelves end up with other stuff and add some lights.
And remember a safe does NO GOOD if you don't lock the door. Heard a few tales of thieves making off with stuff because the lock wasn't turned or the door was left open.
A final thought: A lock only keeps an honest person honest. A safe just makes it take longer to get to something you don't want the dishonest person to get to.
I have thought of removing notched insert and making my own "rifle rods" to support the guns and make more space.