I would cut them back and move them. They are a plant that is best displayed by attempting to cause them to sucker anyway so you picked a great plant to have to move in this manner. I would water them in with some rooting hormone and follow up with usual transplant watering through the year, and I would bet most anything that you won't have a problem. (the bigger the better with the root-ball, of course) Oh, and don't forget to water them very well a day before the move.

if you can figure out how to kill them.. let us know ...

the only issue is how ugly they will be for the rest of the season ...

but you have to do.. what you have to do ...

i would only cut them down.. to the extent that it facilitates moving them ... sometimes it good to have levers and trunks to work with ...

after its in its new spot.. then you could cut it further.. if you want to ...

if you can target a couple rainy/cloudy/cool days ... that would help also .. but see above about doing what you have to do ...

ken

Don't cut them back. If you are going to place the plants under the trauma of moving them out of season - inevitable transplant shock - then they need that foliage and leaf growth to help them recover and re-establish the root system. Cutting back AND moving is a double whammy. And tatarian dogwoods are not nearly as cast iron as are the native species.

Cutting back the top growth of a non-dormant tree or shrub prior to transplanting is no longer an advised horticultural practice.

Like gardengal says, move 'em and wait. You can always trim out anything that fails later, but what DOESN'T fail will help to re-establish the plant.
And like ken says, "if you can figure out how to kill them.. let us know ..."
hortster