Sorry, a single operator is not going to suddenly make things better. A better idea is to look at where the aircraft are required, and set up strategically located bases to service those areas, with an open tender requiring 'x' equipment to service it.
Big companies are not always best.
Don't the comunity helicopter EMS operations belong to the comunity? How is the government going to stop a local area having a service if they fund it themselves?
One type will not solve all your problems either. Why do you need a 412 over a BK for EMS ops only? In fact why would you want the expense of using a 139 when a BK/135/365 could do the job fine?
I have just spent 18 months working in a country which is mostly serviced by 427's and 135's, and which has a excellent aeromedical service using these aircraft. Maybe a look abroad would help.