Anyone here reterminate a SR Master Coupler?

No, can't see why. Got plenty here and the way my stuff is laid out can't imagine needing more than the standard 5-6 ft, of which we have an abundance. Buwahahaha!

Haven’t done a Master Coupler, but I have x-rayed other Active Shielding cables - in order to avoid cutting into one! If all you are trying to do is swap out terminals this will probably be fine. The way Active Shielding works each conductor will probably be within its own wire mesh. That mesh will come very close to the end of the wire, but for obvious reasons not quite all the way.

The wiring at the end will be more complicated, and you will want to try and leave the Active Shielding power supply part alone. As long as you are careful it should be no problem to just swap out ends.

You will of course wind up with a PC with probably a lot less street value. Unless that is you are planning on marketing it as modified by Michael Spallone and rixthetrick in consultation with millercarbon, in which case maybe ask double? ;)