I know from reading Jack's articles for years that while bloodworms are a great food for most south americans and baby discus, he suggests limiting them to adults. Beef heart is used in his formula or used to be, again as a treat it's not bad but not complete for discus. I'd avoid the frozen brine completely though. Adult brine have little to no nutritional value, and they rupture during the freezing process making a mess when you feed them.
I deffinately agree with Number6 pellets would be the best choice if you can get them on them.
I feed frozen brine w/spirulina, frozen blood worms, freeze dried tubifex, discus bio-gold (all hikari stuff) and a custom beef heart i got from my breeder. The bio-gold pellets are the staple, and the others are usually rotated daily so they get 2-3 pellet feedings and 2 other feedings per day. They never get any single of the frozen/freeze dried stuff more then twice a week. My guys are all still young, between 2.5 and 3.5". Also, I only feed the beef heart right before I do a vacuum and WC since it's so messy.
I'd agree with the guys above that regular brine shrimp are somewhat lacking in nutrition, but with spirulina is helps give a nice variety. A high protein varied diet is the best for growing discus