Canada doesn't really have free health care, its just that its more of a convienience thing. Basically, everyone has health insurance through the government. Some provinces charge a monthly premium for this coverage, such as BC, where my mom was paying 30 bucks a month to cover her, my dad, me, my brother, and my sister. Your premium is based on income. If you make less than 18k per year, you don't pay for your health care.
And I think canadians tend to have higher life expectency and general health than americans because Canadians can think "Hrmm, I don't feel well, better go to the doctor to get checked" and they can go to the doctor, get checked over, and not get a bill in the mail for 150 bucks in a week.
One example why I'd hate to live under the US system: My girlfriend. A couple years ago she was diagnosed with MS. How this came about was that her limbs were going numb. Once she was unable to turn a doorknob she went to the doctor. They diagnosed her with an anxiety attack and prescribed her some xanax. Now, she had to pay for the Xanax, which did absolutely nothing. She also got charged 180 bucks for the doctor visit. So after a week of taking the xanax and getting worse she went to another doctor. Another $180 fee. They diagnosed her with MS but sent her to a neurologist to make sure. The neurologist cost her $2000 and wouldn't return her phone calls. So now she's $2400 in the hole just so people could tell her what she had. That doesn't even include treatment. Now, if she had been a Canadian citizen, at her current income, that would have cost her approximately $0, instead of $2400