Probably best to get them in the ground now. There most likely will be somewhat of a setback (some leaves dyeing back and also some of the tender new growth) but if they're growing as well as you say, they've got a decent root system going. After a week or two you should see some new growth and the plants should finish off the year in good shape, If you don't see whole lot of new growth, don't worry. As long as you see some progress all is well as once the plants have a decent root system going into the winter they should over-winter well and be ready to go next spring. Next spring, let everything grow because the crown (rhizome + roots) didn't have a full season to mature so basically treat them like first year plants just to be safe.
As for how to transfer them, just turn the pots upside down while supporting the above ground growth with your other hand and then place into a prepared planting hole. (If this is what you're getting at)
