Something on j15t from shilao podcast recently. They said that it is maybe 100 or 200 kg heavier than the original, but is equipped with more powerful engines, so should have no problem taking off from cv16 with load. It is expected that as j15b join service, they will eventually be moved to the stobar carriers and replace the first generation j15s.
I think something we need to wait to confirm is whether the production J-15B will be using WS-10 or Al-31.
The J-15T demonstrators were powered by WS-10s, but a few recent images of J-15B that display its engines, seem to have a consistent appearance with Al-31s rather than any of the WS-10 variants.