I have another project. And it system looks like envato's websites. For example when you go http://themeforest.net/ you can see under the header top bar there is codecanyon, videohive, graphicriver etc. And i want to build a system like this.
Think this; one site top of everything. And 4 or 5 sub site connected to top site. They should all use same header, same footer, same users. When user signup he can use all sub websites too. Multisite feels me good tool for this but is that achivable? Like same header,footer,users etc.