Experienced growers say "nutes are nutes, there's no difference in N and N." If that's true, it seems like all you're going to test is the NPK ratios of each product. Wouldn't it be easier to workout the NPK ratios of each product (using info on the label) and compare those ratios side-by-side using the same fertilizer products (mixed to get those NPKs)?
The only flaw I can think of in that reasoning is that NPK printed on the label is a minimum guarantee, not actual NPK content.
I guess I don't understand why radish growers don't spend countless hours comparing products. It seems like it has to do with how there aren't 100 competing products for radish grower dollars. It seems like comparing products validates the perception there's something significantly different about them other than their NPK ratios(?).