I think it's almost always a bad idea to create a subconscious association between your brand and something that doesn't work properly. Yeah, maybe the rationa

I think it's almost always a bad idea to create a subconscious association between your brand and something that doesn't work properly. Yeah, maybe the rational user will conclude that the 404 was somehow their ISP's fault (although I, for my part, tend to regard 404s as a sign that either the link or the site has aged out of existence). But convincing the user's conscious mind is only part of the battle. At the subconscious level, you've just lost: The user now associates your site with brittleness and broken promises. I think it's probably better to test with a "beta" page, or a "coming soon!" mailing list, or something other than a metaphorical brick wall.