Huitong does have a lot of credibility in my opinion. However, the sources he use are the same source that the rest of us all have access to online. Anyone who follows Chinese bbs very closely can come up with a lot of the similar news that he came out with. A lot of things he states are in the line of "it is possible", "speculations are" and such. In those case, it normally comes from someone putting that speculations on Chinese bbs. I would say that J-10B is certainly used to serve to test out a lot of new subsystems that will eventually be adapted for J-20, but it is also developed to be deployed into service.