The deal breaker for me would be the hook system. The Juki is a semi-industrial with a rotary hook system, what that means is the hook spins in one direction and can spin very fast giving you the high sewing speeds. A class 15 is an oscillating hook, what that means is the hook moves back and forth like a pendulum on a clock and is not nearly as fast as a rotary hook machine. Both systems work, and both have their fans, but for me a rotary hook system works more reliably and is practically jam proof.