My one and only trip to Africa was for plains game and I took my Blaser in 9.3x62. That is about where I would list the start of the "big bores". I have a lovely little double rifle in 9.3x74r that I was able to use on a Wood Buffalo in northern Alberta.
I have a variety of .375 guns, three of them in the HH and one 375 Ruger. From there I jump into the Winchester 95's in .405, and one lonely CZ550 in 416 rigby.
My .458 American (2") has been used for a few black bears and my cougar. The other "45's I have are BPE (black powder express) guns in .450 3 1/4". One of them is a SxS hammer gun that has accounted for black bears and deer. Just downright fun to shoot! I have another BPE hammer double rifle in a fun 577/500 no.2. The cartridge looks pretty intimidating but shoots with recoil in the .338 range.
I am down to one double rifle in 470 N.E. that I am still hoping will make the next trip to Africa with me someday.
The big boys are fun to shoot, but the older I get, I keep going back to more moderate guns for all the hours of range time and normal day to day hunting.
Sounds like you have quite the collection. Which double did you go with? If I ever grabbed a 470 i think I'd lean towards one of the German makes (Heym, Merkel, Kriegoff). Unless it's in a double I don't see myself going larger than .458.