but twins are not imune from "land immediately" either
Nope, most crashes happens due to the guy(s) behind the controls that c..k up in some way, and it does not matter how many engines you have on your back. However, the odd times when an engine failure does occur, it is nice to be able to make it to the next clear patch....
BTW, all single rotor helicopters have 1 MGB..... and it is usually not a problem