Running shoes-weight

I weighed my running shoes last night. I weighed the right shoe of each different pair, and came up with weights from 13.7 oz to 15.2 oz. The lightest was a Nike Air Alvord trail running shoe, and the heaviest was another pair of trail running shoes: Nike Air Max Assail’s. My non-trail running shoes Nike Air Pegasus and Nike Air N-Sights came in the middle. I have read that over distance, the weight of the shoes I am not sure how much of an affect this small weight difference would make. I am sure it would make some difference. Imagine taking two pound weights, and attached them to each ankle and then trying to run. That is 32 ounces each. It would be tough.
Some runners run barefoot, but then they have wear and tear on the bottom of the feet. What abouts shoes with no cushion. There is probably middle ground where you get the most cushion for the least amount of weight. Not sure what that would be.