No doubt with the increasing prevalence of UAV operations testing will be done. In the meantime, if you have the opportunity to get close to one in the ground, have a look at how small AC are constructed. The blades of a tail rotor on a jet ranger Heli for example would be unlikely to fair well during high RPM operation and imoact with a phantom. A mate has small Robinson heli's and he is a lot more frightened of a wedge tailed eagle than the bird is of the AC.Language is important when discussing the threat of consumer drones to aircraft. Yes, even a 2-lb. Phantom "could" take down a helicopter or private plane but what are the statistical odds? That's why we need rigorous independent testing of drone-aircraft impacts before we draw too many false conclusions. Geese are known to take down large commercial airliners --- but it's a very small percentage since most birds end up as bloody feathers as the aircraft keeps chugging along like nothing happened.
Even if the chance of catastrophic consequences is unlikely sightings of UAV in close proximity to full scale AC just fuels the opportunity for community hysteria and likley restrictions being placed on the hobby.