Better stick with copper core in my opinion (it's what most of the classic bike Electronic Ignition manufacturers specify)
The Nology leads are spiral wound offering 300Ω per foot of resistance - it's not a lot, but you already have 5KΩ caps or plugs.
The Nology Hotwires also have a capacitor inline which is supposed to create a hotter spark.
I have no doubt it does, but cannot help but feel it could upset the guts of the EI unit along the way - we have no sensors or ECUs to compensate for changes like this on our bikes.
I think you'd also have to re-time the bike, as the capacitor loading up and discharging will take time - it will be milliseconds, but unless you re-time, you would negate any benefit.
Then would you get lumpy idle? (possibly, unless you have an EI that has Idle Stabilization circuit like the Tri-Spark)