The .450 and .470 are the same class. The ballistics for that range of NE's is virtually the same. Except the .450 has more bullets to choose from.

I would be happy with a .450 class double rifle and am, but would not say no to a nice .500. Harold Wolf also wrote about their being a noticeable jump in a .500 from the .450-.475 class of rifle on the effect on elephant.

I would also try a .577 too.

The trade-off on recoil and the weight of the rifles are important factors to take into account.

I think my .450 is 11 3/4 lbs and it seems OK to carry for long periods. My camera gear however is NOT so easy to carry!