I have gravel in my tanks as well, I simply feed in a controlled manner, the fish eat one pellet at a time until I decide they have had enough. They are all trained from an early age to eat at the top of the tank, so the sinking pellets don't make it past the first inch or so of the water line.
I don't just toss a handful of pellets into each tank. (allowing the water soluble vitamins to leach out) This is how I feed FH of all sizes, from 1" juvies to adult, whether I use sinking, or when they become extra large in size, floating pellets. The fish are always fed measured portions, in a controlled manner.
A high quality fish food will bring out the wide spectrum of
natural colors in a fish, not just the color red, yet at the same time it should not cause a fish that is naturally white, to turn pink, or a fish that is naturally yellow, to become orange. When these
unnatural color enhancements take place it is typically caused by excessive use of
synthetic color enhancing agents. (such as Carophyll Pink) These are the type of short-cuts that you will see with lower quality foods. They use low cost ingredients & simply jack the color enhancing agents up. (especially for red)
If you don't think that diet plays a role in the development and color of a fish, you haven't been keeping fish very long. Large humps are not created by "high protein", nor is massive amounts of protein required by a FH to develop properly. This is another misconception created by people who are ignorant to the science of fish nutrition, as well as the genetic make up of all FH. FH are omnivores, and do not require massive amounts of protein to develop properly & grow into MP fish.
The foods that are marketed specifically for FH are based on hype, and consumer ignorance. All high quality fish foods contain the same amino acids (protein), fatty acids, Omega 3, carbs, etc, as the ones that are promoted as being "hump boosters".
Are some foods better than others, absolutely, but without good genetics a mediocre FH will remain just that, mediocre.