Digging will absolutely wait until spring. As that time gets closer I will have to figure out exactly when is best(right before growth shows/as new growth shows/just past final frost). For now I am trying to do all of my planning so I am ready when weather permits. I also didn't mean to say I "wouldn't bother" if it didn't style well. I want to make sure I am trimming in the right direction to get favorable results. If the nandina mostly rebuds right beneath the cut I am just going to be limited to the uprights or maybe a broom style. I have not done a complete trim to final shape yet so my visualization is not so strong. Worst case I have a few to work with so I will try a couple different things and keep notes.

It sure doesn't sound promising. If you clip it all the way back to the ground with no evidence of living tissue, I'd not expect it to come back from the roots.

I think someone asked a smiliar question before. Nandina is both a great shrub and dieback shrub, the later of which is how it will perform in zone 6. They do recover quickly, but are still best sited in a protected area. I've had "Firepower" that usually (not always) dies back to the snowline but regrows... Being a dwarf, it is often covered with snow which does help to insulate it and prevents further stem kill... It has great color in fall/winter...

We've had n. compactas do very well in full sun until mid-afternoon, full sun from mid-afternoon, and just morning sun in an eastern exposure. Believe the bit of shade does help them get through the north Texas Aug/Sep heat with little supplemental water. Tough plants, so might be fine with a full day of sun in an irrigated spot. The only nandina we've had succumb to our heat was an ignored 'Gulf Stream' dwarf getting full afternoon sun on a west facing fence in a sloped unirrigated bed - though not sure the dwarf lines are quite as robust as the compactas and standards. The two n. compactas on our east wall are now topped out at about 7 ft after ~18 years. However most of that time, the one shaded by oaks remained 1 to 2 ft shorter than the one getting full morning sun. The standard n. domestica that came with the house reached their terminal height (~9 ft) in full shade by something close to 20 years. So they're capable of eventually reaching full size even in heavy shade, but can get there much faster with a bit more light.... plus the color is usually somewhat better. When you transplant, don't give up on them too soon. We've divided and moved n. domesticas/compactas all around our lot. Depending on the timing, they may drop all their leaves and not leaf out again until the following spring.