There is a place for everything, including singles, but operating in the police/ambulance role over urban/hostile territory is foolish. Cheap, but foolish. This is probably why Sid posted in the first place. Accidents will always happen, no matter how many engines, but try to reduce the risk as much as possible. I totally understand those who support the concept, especially if the alternative is nothing at all. My ONLY beef is people coming forward saying that it is just as safe. It isn't, the end.
If you come forward and say that the risk is higher, but acceptable to the authorities, then game on. In the minefield of litigation post accident, the lawyers would tear apart any such statement.
Let's call a shovel a shovel.