Kens a good guy.. I did a discus talk for his area fishclub once. He used to be a sponsor here years back before he got really big and busy. Your questions a bit tough to answer.. Kens sells alot of different foods.
If you haven't bought it yet.. look carefully at the ingredient list.. best to avoid artificial preservatives and feeds that are high in corn and flour. Look for quality protein ..avoid feather meal, and fats are good.. crustaceans are great.
I never have much luck with flakes for discus...I know some do. I prefer pellets. For me an ideal size is 1mm for a pellet..thats what I stock here.. .8 mm is good for transitioning foods. You need to be persistent.. feed the new food exclusively for several day.