My ex Marine friends tell me that, if they had a man down in Borneo, they always tried to get a Navy helicopter for a medivac as they were more likely to cope with whatever clearing was available. The instructor who taught me to fly was RAF and based at Boscombe Down. One of the many aircraft he flew was a Beaver. At that time there was a flight of Army Beavers at Old Sarum and these guys used to go out looking for difficult fields to land in. My RAF instructor was not even allowed to land his Beaver at Compton Abbas, or anywhere there wasn't regulation fire and rescue facilities.