I am building a largeish well complicated application with Zend Framework now i've found the HMVC model makes managing this application pretty much childs play but my question relates to if it would be more efficient to instead of making each of the component applications(forum, gallery, blog, stories, account, shop) into modules of one large application or if it is better to separate these into sub domains using MVC per component application?
I am expecting a load of between 1000 and 10,000 maximum registered users with perhaps no more than 500-1000 at the same time.