Typhoon Yeah… they hooked mine up fine…
I don't know if it makes a diff but it might depend on how the line is connected and the refer installation. If you have to connect the line to the fridge before the refer is pushed back in place maybe copper is not the preferred material due to the possibility of kinking. My kitchen refer is like that and I used a flexible stainless braided line. I have one down stairs that the back is open to the utility room and I used copper and installed it after installing the refer. I think the braided stainless is the best over plastic or copper. I have all hose connections in my house with braided stainless including toilets, sinks, washer, refers etc..
I am not a plumber and I did not stay in a Holiday Inn last night.