That is wrong, the first Hellboy post is correct. There can be as much as 20fps difference between 1066 and 1333 given the same timings and depending on the app - but mostly its less than 10fps and quite often no gain at all. Things like encoding which are cpu bound see no gain from faster memory. Gaming will see a couple of FPS generally.
Is it something you'd notice - I don't think so. Maybe thats what outlaw was trying to say.
No real big difference, however, prices of ram are quite obsolete seeing as for an extra 2 bucks you can bump yourself up to the next ram speed. So $2 can translate into a little higher fps, nothing significant, but honestly, why not get those extra 4 fps when you max out the settings on SC2 right?