Hi! I'd like to upgrade my mid 2010 15" mbp from 4gb to 8gb, which is the limit. However, I can't seem to find 8gb sticks at the 1066mhz speed. I wouldnt like to buy 2x4gb sticks as they would be worthless if I ever upgrade my mbp, because then I would want 16gb. So will there be any issues if I grab just 1 8gb stick of a higher speed, lets say 1600mhz?