You will make as much in your first year or two with an airline than you will at any EMS job. Now if you've been at the same helicopter job for the past twenty years then it might take you 3 years to get back to the same helicopter earnings. With your experience you are not competing with the kids at 2000 hours. Any professional Helicopter pilot worth their salt can be at an airline above the regional level in less than 2 years.
Not only will you make more in just a year or so you will be home even more too. I do three 3-day trips per month but leave the house at noon on day one and am back by noon on day 3. Doing helicopter math that works out to only being gone for 48 hours - and I'm counting drive time to and from the airport in there. Times 3 works out to the equivalent of 12 EMS shifts per month. For fun I'll go in on a day off for a quick out and back and be home in time to pick up the kids from school.
Keep telling yourself that Part 135 helicopter flying is so awesome. I did it for 15 years and can tell you I thought I had it good. All I can say is I wish I had made the move earlier.