I am confused that speaker cable companies would take the time and effort to produce cables that employ different metalurgy and guages of wire in one cable run, if they didn't believe it could make a difference in frequency and time delivery??? Theo, the propagation "time" differences would be below experimental limits of measurement... electrons run fast -- at close the speed of light in fact (that's faster than a Ferrari). WHy would people produce these? Maybe because it's a product likely to be purchased... As to gauge, you could try very thin wire that would typically favour transfer of higher frequencies vs.. thicker cable that would favour lower frequencies.
Two cables (biwiring) reduce the possibility of intermodulation...
The easiest is to try! Cheers