They are different in kind, not in degree. Opt-in means that no state that has even one legislative house controlled by Republicans, or has a Republican governor, will be part of it.

And then, because it will be too small to be very effective, at least in cutting premium costs, the "public option" will be deemed a failure.

There are more ways than one for the insurance industry to skin that cat. And the only ones who feign naiveté about this are “centrist” Democrats. Maybe including Obama.