I don't *think* the dielectric impact is as significant when it comes to the exterior shield jacket vs. the conductors.
Though, without a doubt, the tight teflon jacket allows less relative motion between the wires and the shield and also less shield distortion. Any motion there could cause mechanical noise. I should probably do some flex tests to see if any noise is introduced. I have noticed that some of the silver teflon cable is not that well shielded when compared to other quad mic cable. The schoeps active cable is perhaps the heaviest shield I've seen (and it is bare copper, not clad, go figure).
I also worry about the dielectric impact of the epoxy in the stubbies..
And in terms of cable sound, I think we really need to do a quad vs. single pair silver teflon cable comp. I now have both types of cable.. I think the quad is actually more flexible.