The safety is OK if you remember to push it off safe before you want to fire.
Coworker that is not a big gun guy relayed a story from this past season, he was hunting with his grandson when a huge buck came out, he was coaching him on when to take the shot and reached over and put the gun on safe (the safety was already off) at the shot he got click instead of bang. thinking it was a dud shell he levered in another round and click again, well the buck had enough of that and ran off, said he felt terrible and the little guy was almost in tears.
Like any other safety, make sure you know how to use it under pressure.
That said, I do not own a modern Marlin with the CBS yet but will probably pick one up in the future.
Rick