I got an old Macbook Pro Early 2008 4,1 and I'd like to upgrade the ram from 4gb to 6gb. I know that by doing this, I will lose the dual channel ability. Is that a big performance loss? Also, I don't seem to find the other sodimm in 4gb single, currently I have the M470T5663CZ3-CE6, but I can't find the corresponding 4gb from samsung. Will there be any issues if I get a sodimm from a different manufacturer? Thanks!