Incidentally, engineers are often a lot of fun to cross-examine, because all you have to do is insinuate they might not be the smartest person in the room and they will absolutely burn anything and everything to the ground--including their own reports--to prove you wrong.
They can walk away from a deposition feeling like a million bucks, and then 6 months later be like "what, who is this 'Daubert' guy that the judge trusts over me?"