I've used it almost exclusively. Use rep-cal every so often. My cobalts have been raised on it with some of the rep-cal. They are healthy and breeding. My final analysis will come once the tads come out of the water with no health problems.
I do know that some people are aprehensive about it. For good reason. There is no reason to change what works for people and I would also recommend the rep-cal/herptivite combo based on what other's experience.