I think the catch is in your last sentence, avoiding root damage. Depending on the size & plant I guess, fibrous roots or a long tap root for instance

yes as we said at the time it will depend on how much root damage they have sustained. We also said that the top may die and you may get side shoots from ground level.
I hope they have survived for you. A neighbour moved 2 to different parts of his garden 5 years ago. One has done well and is clearly flourishing, the other looked fine but slowly started to look less healthy but died about 2yrs later. The damage to the roots was just too much for it to cope.

I have moved plants many times over the years and am always pleased when those that are noted for being difficult thrive. The plants clearly don't read the books!

Please keep us posted on their progress.

Sorry to hear you were apparently displeased with the advice you got but glad to hear the plants have survived..

My post was geared to advice given off the internet and research - Not necessarily this site or advice that I got here.

Most websites I Googled said that Cordylines do not transplant.
Some garden experts even said that they have never been able to transplant a cordyline and that they have always died.
My post was geared more to those who want to move a cordyline. Dont always believe the stories you read online.

I moved two and they are both doing really well. I removed the fleece today as it seems to be warming up and there's a full head of beautiful green foliage. :)

Brilliant - that's good news. And we need to remember that general advice doesn't always apply to the whole country and you are in a good place for that kind of plant.