ruin a day of diving. Same goes for a mask strap or O-ring as well. I keep extras in my save-dive-kit ... including 3 or 4, 2" fastex buckles and even more 1" buckles. They are quite useful for lots of things. I even keep zip-ties in there to handle other minor "emergencies". I guess I was taught "Be Prepared" so deeply as a Scout that I bring it over to my diving.
My buddy at the LDS is priceless. We were talking about this very thing today, when he says... "Oh yeah man, they break all of the time!" so emphatically that I was just plain shocked. I asked him if he had seen this, to which he replied "no"... and then when pushed further, he started to realise that it was just an urban legend that he had been helping to keep alive. Go figure!
There are too many times when someone wants to make a point about how "unsafe" something is, that they make an "assumption statement". In their mind they must be breaking all of the time, so they have no qualms about stating this hypothesis as a reality. No proof- but it bolsters their argument about just how "unsafe" they must be so they make this statement (which is still just a lie). This is also true about some of the arguments against bungeed wings and the need for horizontal ascents.
Now, am I saying that I dive with one of those buckles on my BP/wings? Nope... I just like it as simple as possible. That' my preference, and I don't need any other reason for doing it that way.