Synergistic Research XLR: New Foundation SX versus used Tesla Precision Reference

Seeking experienced input.

Basically, I'm trying to complete my full loom of SR cables in my system with an 8-meter-legnth of XLR's between my line stage and power amplifiers.  The system is wired otherwise with SR, mostly Atmosphere level 4 for interconnects, speaker cables, and power cords.  The exception is SR Galileo SX for power amps.

The Cable Company has available the two options listed in the title of this thread.  The Tesla is 2010 vintage and at the time was near the top of the line.  The new Foundation SX represents the latest design/technology but is 2/3's of the way down the current line up.  Both cables are available for similar money, $2500 range.

Rest of system: TW Acustic LS TT/Reed 3P arm/Ortofon Windfeld Ti cartridge, Hi Fi Rose 150 streamer/digital, Audio Research Reference 5SE and Reference 2SE phono preamps, Pass Labs 60.8 mono amplifiers, Magico A5 speakers, Synergistic Powercell conditioner.

Which would be better, the new lower end model or the higher end "vintage" cable?

BTW, I cannot obtain a loaner new Foundation SX in an 8-meter-length, as it would be a non-returnable custom order.

A new SR Atmosphere cable at that length is more than I want to spend, so that's out.

Any thoughts?  

Thanks.