I have the premium black dragon. I have not specifically spent time a/b ing with the stock cable, but I don’t hear any big differences, but I do think the treble is a little less hit with the moon cable. FWIW, I am not a big cable sound discerner. The moon cable sounds good for me.
What length? I have a 10' of the same grade, and it is my understanding that 5' may be more optimal with taking into account resistance of connectors and solder joints; techy stuff above my pay grade, LOL!