I have taken 5 elephants. 3 at less than 6 yards or less. 4 were shot with my 450 No2, one at <5 yards, my closest, with my 9,3x74R.
I also own a 450/400 3 1/4" double.
I bought the 450 No2 and the 450/400 on the same day. The plan was for my wife to use the 400 on her first trip to Africa [and I would use it here in the US until then ].
If I had bought and hunted the 400 first I might have bought a second 400 for my wife.
I have stated many times and I believe that the 450/400 is the best double for the modern hunter.
If you read all of Pondoro Taylor's work you should see the 450/400 was his favorite calibre.
I used to want a 577 or even a 600. However after using my 450 No2, and shooting 3 different 500 Nitros, I realized the 450 No2 has plenty of power and for me controlable recoil.
Too much power, with its greater recoil can be a bad thing.
For a PH, a double in 500,577,600 where you only shoot at game comming at you at 10 yards or closer, well I can see it. However for a sport hunter who may be called upon to make a longer shot, or pass on the trophy.... Well less recoil may be called for.
I have shot an elephant at 120 yards and a giraffe at 188 yards with my 450 No2, and a caribou at 150 with the 400.
For all round use a 450/400 is the top choice IMHO.
I would not be afraid to face the charge of any animal with a 450/400.