Doesn't change the tonality but seems to have given them some more room to breathe. It's made from "28 AWG 7N Pure UP-OCC Stranded Silver Plated Copper" - or SPC for short. The Noble cable is SPC as well, but a lot thinner and a hell of a lot more flexible.
If progressive/hard rock is your main choice of music and what you spend the most time with then I will say the Noble 4 would be my preference vs. the N6. There's a bit more aggressiveness in the upper midrange and treble, leaner or lower level of mid/upper bass. Overall more flatter sounding which I personally feel suits this particular genre(s) better. Others may very likely disagree.. I'm not a significant listener of progressive rock/hard rock, although I probably have at least 300-400 albums of what I consider the most significant progressive/hard rock releases in my possession but my experienced may still be flawed. Could you name a handful of artists/albums that you really prefer within these genres and my answer could be more precise and maybe more helpful..
Missed this, but it's just the usual suspects. Bands such as Magnum, Marillion, Pendragon, Camel, Mostly Autumn, Transatlantic and so on and so forth. High on talent, low on recording skills (due to budget sadly, though it's gotten better lately!). Anything with a bit of melody basically.