At a prolonged burn-in, yeah, the Mosfets have enough heat that they could do with a heatsink, but that's at 10A continuous. Below that is fine. To his credit, Pixel has stated that his PCB design was not done with 16A continuous load in mind, just the ability to achieve it in pulses, and to that I would definitely agree.
I can't really test at 16A as my household circuit is rated for 15A and the power supply I use will trip the breaker long before it reaches a sustained 16A load on conversion.
I can attest to the fact that the circuit works awesomely, and that it can readily replace any relay board out there that you might want to use. PWM control of the circuit works seamlessly as well.