Not enough to pay double. Lots of 2x8 gb kits starting at $60 at newegg. Some of boards won't even run the faster ram at the specified timings.
Thanks for the info. Does anyone have solid benchmarks to show me? I looked on Google for a good 30 minutes and couldn't find what I wanted. Perhaps my keywords sucked, but the best I could find seems to tell me you are correct, and the gains would be negligible.