I do get what you are after here for trying to stick with BP, I just don’t know if it’s that easy to get working. This would make even more sense in the future as BP speed will improve after epic gets their BP to C++ conversion tool done (my guess would be 4.13+).
The issue we have is not just calling BP from c++, it’s also about substepping running on that other thread. I actually forgot about this but I’ve done BP events that fire from c++ side in the past, I just don’t think it would work with substepping. You can read more about this from here: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums