I have used, and used and used my Medicare. Part A and B. Any medical center that I want to see, takes me in. Medicare pays, and then my 2ndary pays the rest. I meet/exceed my deductible by Feb each year. When I need an extra MRI due to a flair, I slide in the machine, and dont fear what it costs me. When i need blood tests to check liver functions, I hold out my arm, not my wallet.
There are places at every hospital to help those paying cash, or those who are under or not insured, but its alot of paperwork, and not a gaurntee of services. Call the financial aid office of your local hospital and ask them "what would happen if I showed up with cash, not insurance?" would you get a discount for paying in cash? Most discount for cash.
Be prepared to scrutinize every bill that ever comes your way. With or without insurance. I saw a paidin full for a full body radiation treatment on my bill once.

I called the hospital and argued the charge, which even tho paid, was removed from MY history. If you are paying cash, you will want to be twice as careful.
With insurance, they have a main office that sorts out every charge, and argues it for you.
You are bravier than I am. I simply would be terrified to be uninsured. My brother does this, and it scares me. I keep telling him,he is one stumble away from financial disaster.
***edit*** please go to the website and check to see what part of medicare covers what services. it should be pretty easy to look up. This way you can make an informed choice. GL no matter which way you choose.