My tests with double runs of cable vs. various types of jumpers lead me to agree that one of the main (but often glossed-over) benefits of biwiring lies simply in the elimination of jumpers which are inferior to the cable being used. (FWIW, I never used to biwire before I started experimenting with biamping, and wouldn't call myself an advocate of it.) Another variable when single-wiring with jumpers can be which set of binding posts to connect to the amp -- right now I own two sets of speakers whose manufacturers recommend the opposite connections to the amplifier, one to the woofer binding posts and one to the tweeter, and my findings have confirmed that both are right for their own speakers and wrong for the other.
BTW, though I've never used or even heard a Spectron, my own amplifiers (both mooblock and stereo) do happen to be of fully-balanced/bridged topology (and are fed via balanced connections from a fully balanced preamp and DAC). These amps are always in this mode regardless of whether I'm biamping or single-amping, and I still find benefits in biamping.