wayne,
from my own point of view, i dont really thing so.
I used Qualikoi, then switched to Hikari, then back to qualikoi.
Then i met Chris and over the period of two days chris did alot of talking and i asked alot of questions and went home and did alot of reasearch.
The end result was that i switched to Sakura and have never looked back since. It forms the staple of my feeding regime and i add, lettuce, brown rice and molasses, seafood mix to that on a strict rotation (i was doing this before with QK and H aswell), the result can be seen in the condition of my koi.
I firmly believe in and trust the formulation of the Sakura (and the Shogun for that matter, the only difference being the 1% spirulina)
Now i cannot prove it, but my fish look better, have more lustre, are more active than before.