Re: I want Data back...
And the precedent of Lal shows that in the Trek universe, downloading one positronic brain's memories into another positronic brain will not automatically bring the personality along with it. And what we've seen of B-4 to date -- at least onscreen and in the novel continuity -- is consistent with that precedent.
We really don't know. I'm sure Data didn't put Lal's programming in an area that would conflict with his own.
"...the most elementary and valuable statement in science, the beginning of wisdom, is I do not know." - Lt. Commander Data, "Where Silence Has Lease"