The crew in the US is usually nurse & paramedic. Sometimes it's nurse & nurse or even paramedic and paramedic. Or nurse and respiratory therapist. Only a few programs have a doctor onboard. The widespread use of singles is dictated by economics. The 206 and 350 are both, I would say, adequate. The philosophy in some countries is to 'bring the hospital to the patient' (including a doctor in the crew is part of that concept). Here, we 'bring the patient to the hospital'. In other words, the emphasis is more on rapid transport to a place of definitive care.