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My view on the security of them is that they only need to be more secure than your front door or window.
Place them in a visible location so that burglars can't hide whilst attacking them.
They seem pretty solid to me, much more so than the wooden front door frame or the glass windows of my house.
I've used them for about ten years and have been grateful on more occasions than I can count. I'd say the value Vs risk trade off is definitely positive.
One thing though, don't use a memorable date as the combination. It effectively reduces the combination search space down from 10,000 to less than a hundred. An attacker starting at 2017 and scrolling down could try all of the past century in less than five minutes, as opposed to an average time of 4 hours to find a random number in 10k.
Why not get a decent d lock and a combination lock key safe to have on the wall of your house or flat. Always keep your keys in there and hey presto, best if both worlds. You can also keep a spare set of house keys in it so you never have to worry about calling out a locksmith when you lose your keys.