Every answer you get will be anecdotal probably... Some folks will have something and found no improvement and others will love that same product. They all have good stuff in them, but too much of anything isn't good also.
The real truth is you're going to have to figure it out for yourself as to what works with whatever method you choose to ultimately use. I think anyone not selling you something tho will say simply, start with the basics and when you have a good understanding of that, make the decision to add or not add things to your grow. At that point, you would know what helps (or doesn't help) you specifically.