Well the StartBoost is an entirely different product that the RE and Heavy16 Roots. So the true test is between those two as I always run StartBoost. But for this I wanted to compare. I use H16, the entire lineup. Like the results and it's worth it for the $$. At least for me.
Without the StartBoost though there would be no additional source of beneficials other than what the compost tea makes. StartBoost is specifically 2 bacteria. One that breaks down salts the other that out competes pathogens.
The RE and H16 roots have the same ingredients. But RE lists it as 4 compounds. Funny how that is. I might be wrong, but if you mix NH4H2PO4 and KNO3 you'll end up with those two original compounds as well as NH4NO3 and KH2PO4. So what else is in those two bottles of salt is a good question.