I fly utility patrols in a H269 i.e single engine piston..
It seems much more accepted over here (US) than back home (UK)
where they would probably require a twinstar (twin squirrel) or something.
Single engine IFR is the norm too.
With respect to the HV curve - when you are flying low level all day long you are probably much more likely to hit something than have an engine failure. (and lets face it - a lot of the time engine failures are pilot-induced ie no gas/carb heat/preflight)