Anybody use a Rebel for tracking birds in flight? Actually I'm thinking more of the 77D which has good tracking abilities on paper. I use a 7D2 and it is great, but it is heavy. The 77D would save me around 400 g, almost a pound. The 7D2 gets heavier each year and I want to lighten up. Getting a lower weight lens is also important but that will be for a separate thread.