Having experienced a total engine faliure while instructing a pilot (for his instrument rating) during winter on an extended cross country (Birmingham, Jersey return), The flight started in the day but departure was delayed. I said I would NEVER fly single engine at night again, 20 years later I have not. Its not worth the risk. Its handy to know how, as an extra skill, useful to get out of trouble but questionable about its wisdom if you have not got at the very least an IMC rating and dont mind facing the prospect of death when you cant see the terrain if the engine stops.
I was very lucky, I was at FL100, in an airway at the start of the emergency and was able to finally glide to a large military airport with 24hr D&D via a PAR approach. This was after having initially declared a Pan call when the engine started to run rough 5 min before it stopped totally. The vibration was so severe that several instruments failed (it was almost impossible to see them with the vibration) I thought that we had lost part of the propellor due to the amount of vibration.
That night I was incredibly lucky, I think that luck like that happens rarely twice in a life time and its a risk I can avoid.
So no more single engine at night for me. At least in IFR day time flight you have a chance of seeing some ground when you drop out of the bottom of the clag if the engine stops, but I pick my days for flights in an IFR single. If the weather is too extreme, I dont go.