Nope.
Not enough to warrant the cost. I mean, if you haven't bought any RAM yet, then sure, knock yourself out, but I wouldn't replace existing RAM. Going from 6000 CL36 to 6000 CL26 is fairly worthwhile (1-2%), but it very much depends on the cost. Again, you won't notice a difference, but people will pay for a small percentage increase even if they can't tell.
thanks for the reply guys, I'll not bother