This is very worth reading. The authors, while coming from a well-known supporter of the Sanders and Warren Medicare for All plans, have now published an objective analysis that is convincing.
It is not a full study. Himmelstein deals only with administrative overhead. I can also fault it for assuming that a state-run system here in the US would be as well run as the Canadian system. Canada lacks the huge diversity of delivery systems with religious, ethnic and pseudoscientific health ideas. Administering that mess will be expensive!
And, the M4ALL administrative fix, does not address the even bigger issue .. why do procedures here cost so much? My guess is that we overspend on the workers from physicians to janitors. In many states, healthcare is now the biggest employer! The unions will not be happy if we cut jobs.
Himmelstein Single Payer paper