I am not talking about MA. Those programs were ruined from the start:
http://economix.blogs.nytimes.com/2012/10/16/why-private-medicare-plans-dont-cost-less/
What I am saying is that if you compare private insurances across the board they are the premium option- they have higher reimbursements (aka incentives for the doctor to slot you in over a Medicare/caid patient) and often cover procedures Medicare won't.
The closest comparison is comparing private prisons to public ones.
As long as cutting benefits is a political decision that could cost you a job, then at the end of the day private health insurance companies (a long time bad guy already) have more wiggle room.
The problem is that any number you pull up on the current system is suspect. The problem is that we can't even afford "efficient" Medicare. The only way to survive financially is to roll back care substantially: aka offer less care.
Private insurances have shown they will implement the things needed (caps, high deductibles, etc.). Politicians have shown they will throw out the cost savings if, for example, Florida might lose them the next election (that is why Medicare Advantage is a mess).
I trust the markets to cut the flesh to the bone when the time comes.