Since I could not have SWELL on my 2013 Supra SA, I put FLOW on it. I think the improvement is significant. It definitely cleans it up and increases the size, I have had the best luck on setting one. But, I think it is still more about convenience then getting the absolute best wave. The best is probably still gotten by a totally sacked out, listed boat. But I like the idea of just loading all the ballast evenly and just flipping the FLOW for different side riders. Even with FLOW, the wake is improved by putting a few folks on the surf side.
So, maybe it's not the magic wand, but it was worth it to me for the convenience.