I'm about to purchase memory to upgrade some MacBook Pro's with 8GB but the difference in price between the 8GB kit (2X4GB) is just $4 difference with the 8GB (1X8GB) stick. Will a MacBook Pro Late 2011 model allow for a mix of 1X8GB stick plus the stock 1X2GB stick and combine and work properly as 10GB? If not I'll replace both 2GB sticks with 4GB each. Thanks!!!