Gotta agree with CDAT...moisture and movement have been issues with wood since man cut the first tree. An informed client is a happy client! With all the new composite flooring options I am surprised that people continue with hardwood. That being said, a 1/8" gap "throughout" the floor is excessive and the underlying problem should be found. While wood does shrink and swell with all things "Godly" it should have some continuity. Try the humi first and good luck!