I'm in the process of migrating 5 vB forums to XF, only did one so far, the more I learn about XF, the more reluctant I want to proceed. No doubt XF 2 is much better than vB in many ways, mainly the integration with various social network sites which makes the registrations much easier, more intuitive user interface, excellent mobile experience. I can see XF 2 has tried to apply all kinds of new design framework or popular concept, but the forum has become too heavyweight, it's scary that the thread list page needs to include 175 php files, performance is no longer a concern. More customization will be done with addons, it not only makes it more troublesome, it also slows down the forum. I don't like the responsive design either, I wish I can customize the PC and mobile version separately.