Once again, my suggestion is to not over think this.
I love my 416 rigby in cz 550 -- bedded, bolted, a little trigger work. I shoot 400 gr TSX / Nosler at 2400 ft/s and the shells almost slide back into the resizer die when i reload -- I like that in Africa. Same principle as a .470 double rifle, the empties fall out of the breach with a tilt of the rifle, yet both these hit with a huge force which is very sufficient.
Yet, my ph in s africa who shot more dangerous game then any one has the right to, uses a beat up (and I mean beat up) rem .416. welded / epoxied on iron sights, you can see the trigger through the wood stock, ....that beat up -- yet he loves it, it shoots like a lazer and kills everything ( and I mean everything). Sure he is supposed to be the backup only, but I used it from time to time and it performed flawlessly with factory ammo and was a pleasant rifle to shoot. It killed every animal it hit (and killed well). No better then a rigby or a .470 or no worse. I always thought that the .416 rem would be "overpressured" as well - but I learned differently.
My feeling is to fit a large bore properly, learn how to shoot it well, quickly, without flinching, and go forward to smite the game -- they all work well. If you want to go whole hog with a rifle -- well, that is what the hobby is all about - getting a rifle of your own that you are proud of. The ruger, cz, mauser, win, brno, yes even the rem (without the crf) are all good, usable rifles that are used to great effect by the owners that know and can shoot their rifles quickly, accurately and reliably.
I have never found that reliabilty stems from a brand of rifle - they all need to be "sorted out", but once there - I depend on every one to the same degree, but pick the one you want for that game you seek, that is the fun of it.