Like was mentioned above, you'll set the plant back very slightly but no where near to the 'scratch' level. Understand that these plants can produce much more energy than is needed to sustain their top growth. Where does all the 'excess' energy produced go? Into the crown for use at some later date(ie: the next growing season).
It's always very interesting to dig up a 'one-year-old' plant and see what has happened over the course of the past growing season. Normally you'll find that that little rhizome has 'fattened' up tremendously and has developed some serious tap roots, along with many other feeder roots. In respect to what you started with last year, you now have much more energy stored up and ready to provide generous amounts of top growth and in addition, you have a one year old root system already formed to enable the plant to pull more nourishment from the surrounding soil. This was not in the equation last year so the only energy the plant had to utilize was what was stored in that little rhizome that you planted.
There's a lot of 'stuff' taking up space in my head and most of the time I have a hard time putting it down in a usable form. Hope you can make some sense of this.
I've had great results in moving plants in the Fall or Spring. A Fall transplant is usually easier for the simple fact that the soil is much more workable at this time. Another 'plus' is that once moved, the plant will begin to establish roots in the new location until the soil freezes. In the Spring, when the soils are much colder, the rooting is set back until the soil temp warms up to a suitable range for the process to take place.
