I actually sat through a webinar in late November / early December (can't remember exact date) where Behringer staff talked about what X32 can do when used in combination with Sonar.
It seems to be a quite powerful interface with lots of routing and FX options, but at that time it was not working as a DAW controller. Behringer claimed to be working with Cake staff on getting something together that should work off the Mackie protocoll.
I haven't seen any annoucements since, saying that something was accomplished meanwhile, but I read a thread somewhere that people can't get X32 to work with Sonar (but that might actually date back to October).
Considering that not even the Mackie.dll that comes with Sonar is working as one would expect (no pro channel controll), it might be a while until Cake and Behringer turn the X32 into a proper controller for Sonar.