Quicker than copper hard line/response more like plastic?
If it is, I'll order one for sure.

And can anyone tell us why the line material would matter (it sure seems to, but I'm not bright enough to figure out why). [/quote]

THE Plastic line is just a hazard, in a fire it will burn and leak oil, just fragile
THe only reason a large line responds better is just that, the pressure change responds quicker because of the larger line, thats all. Its not the material , its the size