when i've compared tetra foods to other brands, like omega (for example), the list of fillers and other grain based products in the tetra foods are much higher up in the list and with greater abundance than with other foods (like omega). IMO these fillers make for cheap food that isn't so great for fish. they are fish, not cows that eat grain. lol.
i am in no way saying omega is the best food, that is just one that i am using as an example. i feed mostly omega and nls to my fish, along with occasional frozen bloodworms, silversides (for the big fish), and algae wafers and zucchini.
i have in the past fed the tetra crisps to my fish in addition to the frozen foods, algae wafers and zucchini, but found with their current diet listed above, with omega and nls as their 'dry foods', they are much more active and generally look much healthier than before. i still have some of the same fish that were fed on tetra in the past, so it is a true comparison in my own tanks, not just comparing fish A on diet A to fish B on diet B.
while i have never kept discus, i would imagine that fish health related to diet is the same across the board, and discus are no different, eh?