The Duc Pond

It’s pretty well-known by now that you’re supposed to maintain symmetric pairs of RAM in your computer to take advantage of the double data rate. These benchmarks performed by OWC seem to indicate otherwise, however (at least for MacBooks). The advantages of having more RAM (and thus avoiding having to use the hard drive for virtual memory) far outweigh the loss of DDR performance. They test Photoshop performance and gaming.
http://eshop.macsales.com/Reviews/MacBook/Testing/Memory_Benchmarks