I used to have the NAFI AVEMCO. I dropped it when I read the policy and found that what is often to as the "per seat" sublimit was a "per person" sublimit and not just a "per passenger" sublimit. The policy I purchased through my SAFE membership (STARR) where the sublimit only applies to people on board, not people on the ground.
What we call CFI insurance is an additional endorsement on another type of policy.
If you don't own an aircraft, it's going to be an endorsement on a "Non-Owned Aircraft" (also know an "Renter") policy.
If you do own an aircraft it's going to be an endorsement on your owner policy (which usually has non-owned aircraft coverage).