I could be wrong here, but this is my understanding of flake vs frozen...
First, the important thing is not how much food you are adding to your tank, but how much PROTEIN you are adding to your tank.
Most people will tell you that frozen is better for your tank because the package says it's only 5.8% protein. Well, look at the bottom ingredient. 91% moisture!!!! So if we take out all the moisture, then we basically end up with 76% protein, 17% crude fat, and 7% crude fiber.
The flake food I have is 9% moisture MAX. Since it is 34% protein, that means that if you take out the moisture it is still less than 38% protein... exactly HALF of frozen brine shrimp!!!
Yeah, I love the firefish, but they aren't real active. And you should ALWAYS ask your lfs to show you what they are feeding the fish, tell you how often they are feeding it, and to feed the fish in front of you. I once had an LFS employee tell me a mandarin was eating pellets. I asked her to show me, and she rolled her eyes at me and sighed. Well, when she put the pellets in the tank and the mandarin swam right past them she turned red as a beat. Sometimes the LFS workers will misinform you, not because they mean to, but because most of them don't even own an aquarium!