I'm sure this is applicable considering I'd be using the same framwork and what not.
My only issue would be user profiles as there would be user profiles for the mane site and xenforo but I'd also be integrating so maybe it wouldn't be much of a problem. However the user should be redirected to something like http://mydomain.com/users/username/ instead of http://mydomain.com/forums/community/members/nasr.2848/ (used nasr as an example)
I'm sure this is possible with zend as it being the same framework you guys are using but this is just something that I want to know, of course I'm perfectly fine with the user profiles linking to the forums it's just that I'd have a special written system that would tell you how many blogs you've made, how many games and resources you've submitted(which these are shown on the main site http://mydomain.com/) and a few other custom profile fields.
Unless there's a solid way of getting the submitted games and resources stats by how many topics you've made via a forum would probably be easier and a lot easier to integrate into the main site.