The rep-cal dry food is pretty well balanced but I don't suggest using it as a substitute for crickets or other insect foods. It works great as an addition to regular crickets and salads. Many people use the pellets as a topping on greens. It is also a convenient way for pet sitters to feed your dragon if you have to be away for a few days, if they are squeemish about feeding insects.
To my knowledge no studies have been done on the quality of the various available bearded dragon pellets. Some brands are better than others in that they are more readily consumed by bearded dragons. I have tried only the Zoo Med pellets but my dragon wouldn't touch them. The crickets loved it so it became part of my cricket food.
I haven't heard anything negative about any of the pellets now available, though most recommend still feeding greens and insects regularly and not just the pellets exclusively (instead of either greens or insects). Feeding as varied a diet to your dragons is the best way to ensure they are getting all the nutrients they need.
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PHLdyPayne