I have a 375 Ruger Hawkeye FTW 22" with a 3.5-10 power scope and red dot on top (piggy back) and primarily use Barnes 270gr LRX bullets which are amazing between 75-300 yards where I take most my shots with this rifle. I also have CEB 275 and 300 grain bullets I've used on Eland and DG. I use a silencerco Hybrid suppressor
I also have 19.5" Winchester M70 .458 WM with Silencerco Hybrid. I use 420 grain CEB Raptors at 2380 and 450 solids at 2330fps. It has a Holosun 509T red dot mounted and pointed very fast and nice even with the suppressor.
I too long for a .416 Rigby or similar cartridge. I don't see the point in a .500 as I'm not a PH backing up clients. The 416 would be a great rifle for dangerous game with a 1-6 power scope.
I feel as though it is too close to my other calibers. The way I see it you bring generally 2 guns to Africa. For recoil sensitive shooters something like a 30-06 or .300WM and a 416 lets you hunt anything. It bridges long range plains game ability with short range stopping power for DG. For those with more practice and meat on their bones a 375Ruger/H&H AND 458 wim accomplishes the same task albeit with a bit more authority and less chance for animals to run very far if a shot isn't perfect. That said, a 375 will kill anything and without a doubt is the caliber to pick. Last trip, hippo, large eland, and cape buffalo were all taken with a 375 ruger and 275 grain CEB raptors with a single shot each. Hippo at about 50-60 yards head shot and buffalo at 170 yards neck shot. Eland was around 120 yards frontal shot into the neck.
After my recent trip to Limpopo I realized with my style of stop and stalk hunting there are many longer shots that present themselves. When I return next year hopefully I've decided the 2 rifles I'm bringing are a 300 norma magnum (230 grain berger) for long range plains game, and my 458 win mag with red dot specifically for buffalo.
I will loan my 375 Ruger to a friend to bring so I'll actually have 3 rifles there technically.
One thing that shocked me when I went was basically every rifle my 5 PHs had wore a suppressor. I'm glad I fit in and had suppressors on both the rifles I brought.
Just wanted to share my experience and thoughts with you to help you on your decision journey.