I can't help feeling that it all comes down to "horses for courses"- 95% of Ambulance work is best done by road vehicles, 4% will benefit from an Air Ambulance and 1% will require the additional facilities of a full SAR equipped helicopter. (The numbers are made up just like all the best statistics.) The dividing lines are blurred but you would not want a Seaking landing in front of Mrs. Giggings house in the middle of Wolverhampton so that a trauma surgeon can sort out her blocked catheter any more than you would request a road ambulance to come and winch an injured climber off a rock face with their tow rope. The occasions are few, but I have never hesitated to call out the resources of SAR units when required.
Best wishes to you all, no matter what you fly.