About MODx not being as known as Joomla/Mambo : sure there is the time factor but there is also the fact that Joomla/Mambo is a "mainstream" CMS (e.g aimed at end users) while MODx targets webdesigners or people who know their way around xhtml/css and have a least few php basics.
We don’t have one-click install, a block system to place elements without knowing to build a template, and so forth... What we do have is a system which does not get in the way of the creative process (quite the contrary, it empowers skilled people to do what they want

) or produce tag soup

That’s exactly what designers want, and MODx is one of the few flexible, modern standard compliant CMS...
Our user base is growing, but what is good about it is that we have quite a talented user base (I mean, more so than most CMS communities...). It means nice templates, great snippets, plugins and modules. Also, it means faster debugging, new features and great development pace