Spring bypass is in general terms always better. However, and despite the above figure from the freeman is accurate (“1cm piece of 22AWG is only ~0.5mΩ”, 544.381µΩ or 0.544381mΩ according to Electrodoc software), it must also be noted that a proper spring bypass needs to be coiled, or else its life could be rather short. If the bypass is not coiled, it will elbow at some point due to the spring compression, and after repeated spring compression and release it will sooner or later crack at the elbow joint. For this reason the lenght of a proper spring bypass must also take coiling into account. It is only slightly more lenght versus straight wire, 30 - 40% maybe. Cylindrical toothpics make good molds for coiling the wire, by the way.
Properly coiled spring bypasses can last for ages (the solder points are critical and must be done properly).
Silver or gold plated copper clad steel, please. O:)
And please, believe yourself attaining superb springs; with a really high IACS number and thick short prings, you can go much further than before.
“Thick and short” matters, as the lesser lenght in the spring wire means less voltage drop, while some extra thickness compensates for less spring coil turns while reducing voltage drop even more and increasing overall conductivity.