RE: Private nitro/gas/turbine airfield
Some minor distinctions but important points..
The AMA doesn't sanction fields, they sanction clubs.
Your insurance is good wherever you fly as long as you operate within the safety code.
You certainly have the choice to fly on private property, many do. But joining the AMA is helping suppor the orgaization that has been the lead in been working tirelessly for a couple years now, to keep us from being regulated by the FAA. By "us" I mean ALL of us that fly, AMA members and non-members alike.