Titles are tools, and you should use the right tool for the right job. Using the wrong tool at the wrong time makes you look like the tool, but in the right context they're useful.

I've found that using the 'CEO' title can make your company sound more established when dealing with people who aren't your peers - especially when doing business development with larger companies. Back when I was running an smartphone analytics startup, I had a 'CEO' business card for dealing with, say, Time Warner, and a 'co-founder' business card for dealing with indie game developers. This scheme seemed to work fine.