The only problem with Rotators is gimbal lock. It is literally unavoidable and really becoming a critical issue in VR, where you can look straight up or straight down (these are the most gimbal-lock-prone points). Man I am sick of it already. In C++ you can workaround many cases of gimbal lock by converting them into Quaternions (even, though, most of the rotations are still stored as rotators, such as ViewRotation or ControlRotation); no such luck in Blueprints. This really should be addressed if you are seriously targeting UE4 for VR (and you better do!)