@ricred1 - you appear to have Wire World's "best-of-the-best". I also see that you like silver. I'm wondering if the silver elements are working well in your system because the silver is compensating for the laid back ribbon tweeter. Maybe that's why you feel great about your speakers. Silver does not work in my system at all as it tends to push the upper mids and highs (I have a strong tweeter).
The Purist Neptune is copper with gold-plated connectors and is going to sound much warmer/slower than your Platinum Eclipse. Same with any other cable that uses copper only and/or gold-plated connectors (such as Clarity Cable). You might like this or you might not, just warning ya.
There are many very esoteric cable design. I cannot comment on them, but keep in mind that the type of connector also has a contributing factor to the sound.
Have you tried any of the Audioquest upper level solid-core silver interconnects, such as the Wind series? That one is exactly $2k retail for one meter XLR pair. Solid core silver conductors with silver-plated connectors (most likely 21awg as this is what they have historically/typically used). The Cable Company might have this one in their "lending library".
Another cable you could look at is the Audio Sensibility Silver Signature XLR:
I had these in my system originally (before I determined that I did not like silver). It uses 3 different gauges of cryo treated solid-core silver for each for the XLR conductors. They are the OCC solid-core silver teflon coated 20 / 22 / 24 awg.Neotech conductors (making a 17awg cable). The cable is extremely clean sounding due to the solid-core silver. I think it would be a tiny bit warm in comparison to your Wire World because the Audio Sensibility uses Furutech gold-plated XLR connectors. It's about $1052 USD plus shipping for a 1 meter pair. I believe he has a 30 day return policy.