others have but I wouldn't..I live in zone 6 too and I'm not moving or planting anything until next year..my winter break has started!

I would say that as long as you can dig the soil, you could plant now. The roots will be fine, and by now the leaves don't matter. In the past, I have even left a hosta clump on top of the soil over the winter, and it survived well. I am in Massachusetts, zone 6-ish.

does your ground freeze and thaw.. and heave ....

how big a plant ... will it heave out of the ground ...

air temps are rather irrelevant ...

ken