If the Model's ID says she is of Age then Its cool.. And I request all Model ID's and a Signed Model Release with every set I purchase from any dealers.
Besides there is tons of these sites out there..
take a look at
http://www.diaper-girls.com
which is actually owned by a poster here in GFY that Shoots the Content and also sells content and custom shoots and from his own mouth he said its making bank..
so If a respected poster can say that then Im all for it.