Concerning Less Wrong's tagline, consider this plausible reaction of someone looking at LW for the first time:
Cut the crap, nobody cares about rationality in the abstract. Just tell me what view you're trying to push under the guise of presenting it as the only "rational" one.
And here are two real quotes from 2009:
[concerning the ban on SIAI discussion during the first weeks of LW] I think it was so that newcomers wouldn't think that LW are a bunch of fringe technophiles that just want to have their cause associated with rationality.
And in reply:
But that's pretty much what LW is, no? I've long suspected that "rationality," as discussed here, was a bit of a ruse designed to insinuate a (misleading) necessary connection between being rational and supporting transhumanist ideals.
The quoted text speaks for itself really. So therefore I think LW's admins/web designers should seriously consider replacing the rationality tagline with something more savory.