Have you done any fmq on your domestic machine? Do you slow down & speed up as you stitch your design because you move the fabric slower in trickier spots? Because you don't have your foot on the pedal to control the speed, the stitch regulator will automatically sense that you have slowed the movement of your machine and respond accordingly. The speed control just keeps your speed constant no matter how you move the machine, which may result in uneven stitch length. If you go with the speed control, you need to ask what it does when you stop moving. It's my understanding that different brands do different things.