I suspect many of us use Git because it was made by Linus Torvalds ( I think everyone agrees that he is a great developer) and is used in the Linux kernel. If it can handle that, then you can be pretty sure it will handle whatever you throw at it (unless you are Facebook, it seems).

Add Github to that mix and you can see why so many developers sleep like babies at night. Of course it's not rigorous, but the choice is not irrational.