Growth is something I can't speak to especially for SPS. I will say that my experience makes me believe that they will be perfectly capable of good SPS growth (based on my PAR readings), but that is purely speculation at this point. Also, I would not even try to pretend that this light is on PAR with the big brands, only that it is a viable budget light. There are definitely some draw backs, the fan is loud (though there is a simple solution to reduce the noise), the mount needs some work, and the onboard control falls way short.
IMO, for the $, it is one of the best solutions available to those looking for a budget friendly light. I have not experienced any disco ball effect with these and they create a decent shimmer, not Kessil shimmer, but decent none the less. The black boxes that I have used ALL had terrible disco ball effect that led me to search for a better solution quickly.