Thanks for posting and I 100% agree with your findings. While I have not gone through the lengths you have to verify I do believe characteristic impedance is very important in SCs and arrived at a design that uses ribbon wire for both speaker and power cable in order to perfect the geometry of my cables, with the PC having very low inductance and high capacitance and the speaker cable being a little more balanced but with very low inductance vs what you can achieve with round wire.
The wire shape also has an effect on image size in many systems, as the wire approaches a very thin foil image sizes tend to blow up and become larger than life, without enough separation.
The conductor material also makes a difference, I have speaker and power ribbon cables in both UPOCC copper and silver, which are identical except for the conductor material and the differences are massive between the two. I've also seen speaker cables made out of "exotic" materials like Tungsten or the foil often embedded in window frames as a weatherstripping, this is not great as the reduced conductivity reduces the system's damping factor, which can make for a big difference vs copper or silver, but it does it by reducing the electrical damping the amp has over the driver, which is not ideal imo, but some like it, especially if you have an mechanically overdamped driver. But you can achieve this simply by using thin-gauge copper wire, you don't have to use tungsten or god-knows-what!
IMO, there is an information overload on cables and many poor designs are on offer, and are vigorously promoted or even SHILLED! Designs are poor for a wide variety of reasons such as not being able to bend the cable without applying too much stress, corrosion from doing ridiculous stuff like not properly insulating the wire from air, using heavy gauge solid-core wire that will crack with repeated bend cycles, etc... I've even been recently told geometry in speaker cables simply doesn't matter!
But hey, I guess these days everyone feels entitled to their own facts...
I can only hope one day more of what we hear with cables can be correlated to measurable metrics and understood so cables can become more universally good, without so much misinformation and misguided designs out there.
