I have had traditional Medicare with a grandfathered Plan F for 10+ years. One of the things I REALLY like about the supplement plan is that I can decide to go to a specialist and not have to get permission or a referral to anyone. I had/have CLL (Chronic Lymphatic Leukemia) since 2016. I had some time to choose a specialist and decided on one in Eugene, Oregon because he did research and saw mostly CLL patients. (Many oncologists will treat this disease, but most see only a few CLL patients each year.) He also managed several research programs so I would get top-of-the-line treatment.
Living in a motorhome full time made it easy to head to Oregon for treatment when I needed it. I am in remission, but I still get blood work done and have a telephone conference with my Oregon oncologist every 4-6 months. My oncologist is probably one of the top 10-15 in the country, and I was able to do my own research and make my own decision of who to go to for treatment!! No bureaucratic hoops to jump through, which is priceless. (Part of my decision, by the way, was climate since I knew I would have to stay there for 3-4 months, and did not want to stay in my RV in a very cold or very hot place, which eliminated MD Anderson for heat and Ohio State for cold! I eliminated Boston and Stanford on the basis of traffic.)
I got brand-new targeted medication treatment, by the way, not chemo, and while I had several monoclonal antibody infusions, I had no side effects from that or the pills I took for a year. Platelets dropped a bit, but no nausea, hair loss, weight loss, or anything else. If I go out of remission, I will head right back to Eugene!!
I chose my supplement through United Health Care and have had exactly 0 copays in 10+ years. That has included several kidney stone procedures, two cataract surgeries, CLL treatment, and a bunch of odds and ends over the years. It also makes it easy to hop into an emergency room or urgent care place with no worries about being covered, assuming they accept Medicare.