Hello, i have a macbook pro, i carry it around in my shoulder bag often. my gf has a macbook, she leaves it at the house. i admire the petite size of her ac adapter. it is 60 watt, mine is 75 watts and feels almost 35% larger.... is there any reason not to use the smaller, 60 watt macbook adapter on my macbook pro? it charges the battery just fine! thanks, r.