Been using it since the 1990's. Its the only calcium powder i have. So every feeding they get a bit of D3. Vet visits always had good blood work and bone density. The vit-all is not really useful. Its meant to be fed to small birds/mamals as a gut load. You cant " powder" feeders with it.
Im old school and use
http://www.repcal.com/supp.htm Herptivite.
But i hear this "preformed doesnt cause buildup but proformed does" is an urban legend that got debunked like 20 years ago. So odds are when the new chameleon comes, ill be getting some repashy SuperVite as it contains both pre and pro formed vit A. Right now the tegu is on Calcium Plus (lives in a hole and only gets UVB a few hours a day) but its too high in D3 for a cham.