Probably my fault for not checking first...
For AC 60Hz/50Hz Dimmer/SSR Controller Board
Three years later finally getting around to using it, but the active range of PWM makes it useless for what I wanted to do. In "voltage" mode it will pulse the motor noticeably while PWM just does nothing for me--likely related to using a 3.3V micro and not trying to do voltage translation. But not much point if I'm only going to get the same range out of this that I get from a cheap controller from Amazon.
Response from RF Simplicity | Sept. 6, 2018
Thank you for the honest review. I've made a change to the PWM detection function to allow for a wider range of frequencies and works at 3.3V. Some motors are okay with a chopped wave, but others need a VFD.
