In my oppinion, if you are very much in tune with the feel of your bike, you will probably feel a small difference. Especially accelerating. But if you're not, you probably won't notice. When I swapped out heavy tubes and tires for the first time, I had saved a total of 450-500g on the wheels, and I definetly felt it when climbing!
But that's just my experience... You'll see for yourself...
With light tubes, it,s important to talk them and keep them properly inflated to avoid pinch flats (the are more prone than regular tubes!).
Hope this helps!
CODMAN