>>4280152>is it really worth doubling up?Well, regardless of sensor size, you usually have to make a choice: slow small zoom for convenience, fast small prime for low light, or fast huge zoom for both. I'd rather have two small lenses to cover both instead of a big ass 2.8 zoom.
So if I was going out all day, taking two lenses that are each small enough to fit in a jacket pocket easily, I'd do that over having a big lens stuck to my camera all day.