i have no experience with this food, but my thoughts about it, from reading the list of ingredients, etc, on the lafeber's website, are:
Likes: It contains Omega 3 and 6 fatty acids. Yay!
A Couple Of Concerns: i) Macaws and cockatoos have rather different nutritional requirements, especially when it comes to fat and Vitamin D3 requirements. Why is the macaw pellet the same as the cockatoo pellet?!? ii) The list of ingredients is short, but the list of added vitamins and supplements is long. I'm not sure if adding vitamin powder supplements to a starch and protein base is the best way to go. Personally, I'd like to see a much longer list of ingredients including plenty of vegetables and fruits in addition to a starch and protein base, because there are a LOT of beneficial micronutrients from a wide variety of foods that just can't be added to a formula as a powder from a plastic bag.
Overall, I think this food will be well worth trying.
One thing for you to note, is that this pellet is not extruded, so its texture is likely to be quite crumbly. Your scarlet macaw and you will have to decide whether this suits the two of you in terms of beak feel, messiness and wastage.