ZTWs have no BEC.
Yes they have three wires coming off them, mystifying to me too. These are ROHS compliant ESCs and use leadless solder. First thing I do with them is strip off all the wires and ALL the solder from the motor pads, power and ground pads and the signal pad and re-tin with the solder I use to get a better connection.
Not that I don't like leadless solder (I don't, it's hard to melt), but that mixing solders provides a poor connection. I do this for any ESC leadless solder or no so I may have the best connection possible.
With all the wires stripped off, I am free to use my own Arduino wires in the colors and lengths I choose to provide signal to my ESCs. I only connect signal wires reducing the wiring substantially.
I like the Pololu voltage regulators. They are much smaller than a dedicated BEC as they don't have that clunky capacitor. Because I am powering a servo, I am using the 1A, 5V output step down voltage regulator which is connected directly to the 12v power harness. I run smaller servo wires as 5v power and ground output from the Pololu up into a 3 pin Dupont, add the signal wire for ESC1 and connect the 3 pin Dupont to the Naze at M1.
The toughest, most time consuming part of the process is removing all the solder and all the hot glue from the ESCs and not zapping them with ESD or overheating them while soldering directly to them.
I should have taken more photos of the wiring details and I may yet. I have everything except the Pololu under the Naze and wired correctly but with a little more effort, I think I can get the Pololu up under the Naze as well and make for a cleaner build.
It's -28 outside right now. It's a better day for soldering than flying for sure.