Has anyone tested solid core wiring from an ESC to a motor?

If you do enough reading you will find that quality solid core wire has less resistance than stranded wire of the same AWG. Stranded wire is to resist damage from flexing and that is fundamental just like resistance is fundamental. I have been running milspec single strand cable for 6 months now and see no problems with it yet. The wires dont get hot and resistance hasnt changed. I do have all of the wires supported and mounted to devices that dont move an appreciable amount.

By the way if anyone is looking to measure for small differences in resistance you can get lab grade powersupplies that do voltage and current limiting for less than 50bucks now. A powersupply with a current limit allows you to bridge a circuit together that you want to measure low resistance values on by creating a low current short and measureing the voltage at a current limit to calculate resistance at very small increments of resistance.

Poor mans LCR if you you want to measure motor or wire resistance. Be warned that direct shorts let the smoke out if you pass too much current. Ask someone who knows a ohms law.

by the way do not try this on a semiconductor. Dont even consider unless its on something like a winding or a wire with suitable current limits.