To be honest it looks like the performance boost wasn't because of the ram speed, but because of dual channel.
He bought 2x 8gb and had 8gb before. He doesn't mention if that was 1x 8gb or 2x 4gb.
I stumpled upon the ram myth last year so I did some testing myself and the boost is not that heavy from my experience.
Some data from cinebench R15:
I7 2600k:
4.2, 1333: 533
4.2, 1600: 553
4.4, 1333: 572
4.4, 1600: 582
4.4, 1600 + HT: 754
I5 2500k:
4.5, 2133: 557
I highly doubt that a few points in cinebench would result in such a massive fps increase for gaming. My friend with the 2500k tested it with Witcher 2. Going from 1333 to 2133 and it was around 15 fps. But it was 150 to 135 fps and not 45 to 60 for example. Scaling!
Tested at 800x600 for 100% taking the gpu out of the testing.
Conclusion: yes, ram makes a difference but it isn't worth it to buy faster ram when you don't need more GB or build a new rig anyway!