Actually, they are quite welcome, since they bloom later in summer and are drought-resistant. On the down side they do not respect boundaries, and spread easily. The wandering roots can be a plus if one is trying to fill space in a flower bed, but they just do not know when to stop!
I wish they were deer-resistant, also.
Hey, this is what I can try: in winter (the rainy season) I will move the invasive individuals outside of a protected area to the hinterlands (what I call the further edges of my yard). This way I can learn for myself whether local deer find rudbeckia irresistible, somewhat tasty or just leave it alone.