Not had an engine failure yet, but did lose 3 spark plugs during the climb out at night.
The engine ran a little roughly, but a quick circuit was safely accomplished.
Having though the risks through, I now prefer to stay in the circuit when flying an SEP at night.
The incident happened about a year after I got my PPL and it was a good wake up call.
I am pretty diligent at glide landings and PFLs now, just in case.