MyBB has an importer for 4.x, but it is not for the latest build. Xenforo could consider building one, if they have a database for it, so it could be included in a future 1.5.x release. If you want, you can contact @Chris D and include your DB for IPB 4.x, so that could help them make an importer that might help others in your situation.
Yes, I sent them my database and files as I also want to switch as fast as possible... IBP4 is just missing too many features, has a lot of bugs and the editor is too slow to be used on low-power devices
Yeah... I'd like to throw in my own request for a converter here. I am not thrilled at all with the direction IPB is taking with 4.1 and would prefer to move one of my largest communities over to XenForo.