I've got the 4GB x 2 1067 MHz from my 2010 MBP - can I use these in the 2011 MBP? If so, would the performance gain even be noticeable going from 8GB 1067 to 8GB 1333 (i.e. if I can use the 8Gb of 1067, would it be worth the ~$100 to purchase the 1333)?