AW139 should be on the short list. Operated in OZ in the EMS role in NSW and QLD, so definitely hot and humid at times, although not particularly high. Both operations are single pilot IFR day/night (night sun and NVG), with a normal crew of 4, although this can be increased depending on the job. The NSW machines are kitted out for one patient but can carry 2 if necessary. Empty weight with all the EMS gear and winch is around 5000kg, with MAUW 6400kg (although this can be increased to 6800kg). In NSW normally operated with 1000kg fuel so endurance over 2 hours with fuel burn around 400kg/hour. Loads of power - almost always capable of PC1. Very capable machine in the EMS role. SAR modes available (autohover, search patterns, etc).
On the negative side - the main wheels will often sink up to the axles in soft ground and there's very little clearance between the belly and the ground, so when landing on unprepared sites you need to be careful of ground clearance (rocks, sticks, bushes, etc). Quite an intense downwash which can create havoc when overflying/landing close to your accident scene and cause branches and debris to rain down on your winching victim.
Last edited by Mark Six; 26th Sep 2013 at 11:00.