I've seen atleast one major industry professional here, but I agree the NDAs that developers are required to sign would be a considerable hindrance to getting that particular line of professionals to the site.

I think, what would be best, is to figure out a way of bringing over those development communities. It's a shame that we won't have access to sponsored tags for some time, but there are many professionals in the indie community, and quite a few with the appropriate skillset among hobbyists.

I never got into UnityAnswers, so I don't know how into Unity would be to driving people here (I would assume very little, although a Unity sponsored tag would probably cost less than hosting unity answers)

But I do know that the UDK community could benefit vastly from having a resource such as this. With UDK practically being Unreal Engine 3, many professionals play with it from time to time.