These Hikari Lionhead pellets are relatively big as they're around 1mm in size, and one of these pellets equals about 4-6 pellets of 'New Life Spectrum for Goldfish' so, you probably wouldn't want to use these for fry/young goldfish, or small mouthed/throat-ed fish. Also these pellets tend to dissolve pretty quick in water, if left uneaten they will basically expand to about 2-3 times their originally size in the water and thus dirty your water pretty quick overtime.
I noticed that these pellets have a very strong smell and can easily stink up an indoor aquarium. That being said I'd say these are more ideal to use for outdoor ponds because it can smell up a room in your house through the aquarium water. For myself, I'd only feed this as a small treat once in awhile if kept indoors, or in small quantities with other pellet food daily.
These can possibly make your fish have thicker fecal matter, and generally the fecal matter is very dark brown in color when only fed this so, I do worry about constipation becoming an issue. This could perhaps be beneficial for awhile if your fish is perhaps having very stringy looking poop.
I really haven't noticed an increase in head growth and such with this, but based on how my fish look and other fish I've seen that eat this it seems to possibly help develop a higher arched back closest to the head of the fish (although the higher backs may come with age and eating in general more so than with this food).
Some goldfish may not be overly into this food as one of my ranchu appeared to like it more than the other, and the one that liked it the most had grown to be about 10 grams bigger than the one that didn't. Which could perhaps be useful if you're trying to quickly grow out certain goldfish.
I did not find my fancy goldfish had gained any real head growth from consuming this product over the course of several months, which was the main reason I bought this to begin with. Feeding this as a daily diet would also not work for myself as the food has too strong of a smell for indoor use in my opinion, and I worry about fish constipation with this product. On a scale of 1 to 5 I might give this a 3 at best.