I don't have 80-400VR lens. But reading the post I think you should think of AF-S 80-200 /2.8 ED. In D100 it become 120-300 /2.8 ED (with FOV factor). The question is are you need more than 300mm view? If yes, go for 80-400, for outdoor ISO 200-400 is enough to get safe speed.
Pinky Mirror Nikonians@Jakarta,Indonesia-- it's near Bali, if you don't know where it is