Seriously considering purchasing an annual plan to cover emergency air transport home in case of critical illness.
I have no experience with med evac insurance, though we have been considering it as we age. Before you invest in a policy (especially a general policy with broad coverage), though, I would suggest you ask specific questions about what is included in the coverage. For example, in the case of critical illness, would the policy cover evacuation to your home or just to the nearest appropriate medical facility? Would transport be by air, or would a less expensive mode be authorized if available and adequate? It might be worth examining WHO makes the decision about evacuation too...the local treating physician and/or the insurer, and what say might you/your traveling companions have in the decision?
Maybe all you are interested in is having some basic coverage, and don't really care too much about the details...you just want to be taken care of in an emergency. But if you really want to be transported home in a medical emergency, I would ask some questions so you get what you want, should you or a traveling companion become critically ill.