In most of NE it's still safe to plant.

I'd plant them all - today if not sooner, if the ground is dry enough to work without turning into concrete. But I'm on the Cape, and we have a loooong slow fall season. I see you're in zone 6, but that doesn't tell us anything about how fast the seasons change in your locale.

The problem I have with sinking pots is that things can dry out without your noticing. A planted, well-mulched plant will have a better chance, IMHO.

I'd plant them now.

today if not sooner,

LOL... you want to wind the clock back??

"Another gardening center said to plant it in the ground in its container, then dig up in the spring and replant. That way it will weather the frost better. "

This part is beyond my understanding...
How and why the plant being planted in a pot will do better than a plant without the plastic wrap?

Suggestion to plant in a pot in a fall and then replant it in a spring make sense only if permanent spot is not available and you are looking for the temporary solution for overwintering.

Mulch around them well to keep the soil warmer now to help with root growth. It will also help prevent frost heaving during thaw/freeze cycles.