I think not so much. Decreased latency will increase mem i/o a little, but it won't have much effect on overall computer performance.
Case in point (personal experience):
Way back when, I built a Core2 system out of an eVGA 680i motherboard, an E6600, a 640 MB eVGA 8800GTS, and 2 GB of DDR2-1000 Crucial Ballistix.
I got the system running at 3.3 GHz. pretty easily (later 3.6 GHz.). I initially set the memory timing to 5-5-5-15-2T. Using 3dMark05, graphics performance leveled off at around 3.2 GHz.
CPU and memory performance scaled linearly with CPU speed. So I started optimizing memory. I worked all the way down to 3-3-3-7-1T, Orthos stable for 24 hours.
Back to 3DMark. Memory i/o increased about 7%. CPU performance increased maybe 2%. No significant increase in frame rates.
I think just the fact that you will have 4 GB of RAM instead of 2 GB will have the greatest effect on performance.
And the price difference between good and cheap RAM is small enough that practically everyone can afford to be good RAM.