While medical insurance was a big consideration, I didn't let it stop my from my early separation at 54. While I often complain here about the annual cost (which went down $1200 when I moved), I'm still glad I didn't wait until 60 to keep the .gov insurance. It has been a small price to be for enjoying life an extra 6 years, and as others said, you never know what insurance is going to do from one year to the next anyway.
I do continue to keep an HSA and use it as an IRA, maxing it out every year and then buying Vanguard total stock and Wellesley with it (the ETF versions, as my HSA only lets me use Ameritrade). I use money out of the bank for any medical expenses and leave the HSA alone to grow tax free.