Every ESC when running in sensorless mode has different programming to determine rotor position. I've had some ESC/motor combos that work terribly and just swap one piece and it works perfectly. Also since you mixed brands, you might run into compatibility problems. A VXL motor and ESC work perfectly together.

Did you get the PC programmer? It's possible you have an older firmware on the HW ESC. Hobbywing and others are always making updates to their software to address specific issues with certain motors. For example this is right out of the README on one of their software updates: "The acceleration is much quicker than before. "