With a mega order of 200 B407GXP I don't see Air Methods paying too much attention to passenger size.
On the contrary, that's why the 407 was selected. For most operations (other than hot/high) the 407 provided better metrics than the other choices B2/B3 and 130. CG issues affect the latter such that routinely 250-300lbs are the max passenger weights possible for the sectors flown. It's not just patient weights that are increasing, but in many cases it's the crews as well, with the pilots being the most critical CG wise of course. In addition, there is an ever increasing requirement by regulators to carry more equipment - in many states the air ambulance falls under the same regulation as the ground ambulance with little distinction made. 175-250lbs of equipment is the norm.
In my opinion the EC130 is a good aircraft in the EMS configuration and a better fit for medical care, with improved access over the 407. From a business perspective I can sell that over many other choices including twins eg. 135. Unfortunately experience has shown that the cg issues which impact the B2/B3, remain for the 130. Of course the health care industry in the US has a very different economic model which promotes single use. That's just a reality which accepts the cost/risk benefit.
As for accidents, it remains a challenge for night ops. The new and improved EC130T2 which comes online this year, will see some additional benefits for aviation and medical crews alike with many new airframes and retrofits. This includes G500/G1000 with synthetic vision, and simple auto pilots - more tools and training. One hopes that coupled to NVG's etc this will reduce the inherent risk of single pilot night time ops, but there is always the human element which cannot be removed from the equation. Where many pilots develop their experience in a single pilot VFR environment or enter the industry from a specialized multi crew background, human factors/training/cultural and proficiency considerations weigh heavily. There is also the shear scale of operations in the US to consider, which whilst not mitigating the need for improvement, certainly contribute to the statistical inevitability.