Quote from Countdown
"...a more apt description would be a simple 'return,' denoting the fact that my neural nets were successfully imprinted onto B-4's existing programming."
That (and the prequel story in The Needs of the Many
) are directly contradicted by Cold Equations: Persistence of Memory
which said B-4's neural net was too primative to process Data's memories, and doing so was causing a slow cascade failure.
That said, I haven't read the the STO stories in the Star Trek magazine, and they may have rewritten things somewhat to fit better.